HELLO YES! you came to the right place! i'll focus on them more separately than together and i'll try not to diverge into analysis as best i can. let me know if there's any clarification you need.

first of all, this is challenging, but throw out literally every single preconceived notion you've ever had about both of them. their fanon personalities really aren't good foundations if you're trying to learn how to write them in character. if you think of minori as a honoka or chika (love live protagonist) type character you've already lost. absolutely no hate to either of them of course (honoka is my muse oshi and chika is my third favorite member of aqours). the comparison just makes no sense.

for minori: positivity is key. ignore the idol fan thing, or the 'girlfail' thing, and get to know that first of all. positivity despite everything is minori's key trait. she's able to spin anything into a good thing - in past self, a bird poops on her bag, and she thinks maybe it's a sign that something good is going to happen. minori uses this positive attitude to combat her inner feelings of inferiority, too - it's not something that comes naturally to her. she's very very strong in that way.

otherwise, relying too much on minori's habit of being clumsy or misspeaking will make your characterization seem cheap and surface level (to big minori oshis like myself, at least). same goes for her being an idol fan. of course, these are still prominent parts of her personality, but using her constantly as comic relief is not quite right (shizuku is usually the comic relief in more more jump's group dynamic, anyway). minori admires haruka very much, and haruka is the reason why she was able to adopt her positive outlook, but if you'll believe me, entire more more jump event stories pass without a 'minori being gay' moment, especially with their current characters (in jp). this doesn't only screw up minori, but haruka too.

minori is determined and positive as a show of strength. she went through a lot to prove herself of being capable of being a member of more more jump. in more more jump's dynamic minori represents fans - not just because she's a fangirl, but because she's the backbone of the group. as what past self seems to say, the relationship between a fan and an idol is two sided. the fans are the reason the idols are able to stay on stage. as minori says herself, "an idol is not just someone who delivers hope to everyone. they also receive hope from everyone." she is hardworking and endlessly grateful.

a few other little quirks of hers: she likes to talk to herself and pretend she's on an idol show. she is better at speaking on impulse rather than planning speeches (according to airi). her parents are realists but supportive of her, telling her "millions of people just like you want to be idols, but if you've decided on it, there's nothing we can do but support you." she likes to write in a diary. she has a habit of over-explaining and rambling a little. she's prone to doing slightly dumb things (mindlessly opening the stage door in front of the entire audience at the end of past self). she bites her tongue a lot. her unique talent in more more jump is a fan's eye - she knows how to maximize exactly what a fan wants to see.

(connected to her habit of rambling - she's used to people finding her overly excited about things. it's how she expresses her love for things; she rattles off everything she can without thinking.)

that said - she's also really, really gay. i don't want to downplay that. she can't look at haruka in the eye for a second without losing her mind. she thinks of haruka as her 'lifelong goal'. but it's because haruka saved her from a pretty dark place and gave her this dream that she feels so strongly about. as gay as she is for laughs, haruka does mean a lot to her, genuinely. but like, especially now, the two of them are completely capable of talking without minori overheating or blushing or whatever. all in moderation.

that brings me to haruka. haruka is more of a 'reactionary' character - she reacts to what happens to her rather than causing things to happen. but like positivity is the key to minori, when writing haruka, thinking is key. overthinking, even. i'll get more into this with some examples in a second, but i want to put that out there first and foremost.

quiet, careful, and professional, haruka is an idol through and through. unlike airi, for example, who has different attitudes on and off stage (not that she's two faced or anything - airi's character arc specifically addresses how her onstage and offstage selves are both her) haruka is a 'perfect idol' because she really just... acts like that. she's charming and kind and formal all the time. like with minori, leaning too much into that isn't exactly accurate, but it's still true.

i'm going to assume you've at least read more more jump's main story - haruka's trauma still very much affects her. she can stand on stage now, and all that, but she's extremely afraid of her words being used against her (more on this in a second). she's quiet and professional because she feels as though being an idol and giving hope is her duty. they're feelings she can't give up no matter what happens to her. this is what painful hope is about - she couldn't quit being an idol in the end because her feelings were so strong. haruka has 'giving hope' on the mind every day, all day.

quick side note: haruka is not great with feelings. like her name suggests, she's a little distant. in HLE, when she notices airi may be having a problem, she asks shizuku to ask airi about it instead of asking airi herself. this goes hand in hand with how haruka didn't smile as a child until she was introduced to idols. haruka shows she cares by putting in work: whether it be to fix someone's problem, or to thank her fans for their support.

now for haruka's love of overthinking: it's a sort of safety net for her. in beyond the dream she's glad she overthinks because she could move forward without any worries instead of being unsure. in beyond the dream, her issue is the media: she's worried about more more jump's message being misrepresented through editing. that's because of what happened in the main story: she's extremely afraid of hurting people again.

otherwise, haruka is very thankful for minori and loves more more jump more than anything else. out of any of the members she probably feels the strongest about giving people hope (in beyond the dream, 'giving people hope' is likened to giving people a reason to live, by the way. that's a lot for a sixteen year old to shoulder.)

a few extra things about haruka: she wakes up extremely early and is very self disciplined. she has the habit of taking things literally sometimes (seeming to think airi would actually 'attack enemy idols' on her show). she has a competitive streak, best showcased in her relationship with an. like the rest of her members, she's very analytical. she can be mischievous sometimes - this especially comes out in some of her habit of slightly passive aggressively teasing airi. she doesn't mind working hard (after all, she loves being an idol. why should she take a break from doing something that she loves?) she is extremely proud of minori and views her as an equal. haruka is quietly extremely gay - it's all about the warm smiles at minori's back and the unfinished sentences with her.

this has gotten extremely long, and i'm sorry. i hope it helps! like i said if there's anything else you want more information on i would be happy to clarify for you (i have more detailed notes but they aren't with me right now). if you want me to review certain scenes for you from whatever you're writing i would be happy to do so as well. i'm really happy that you're at least trying to write them well, a lot of people just give up or don't care. have a wonderful day!