I’d generally go rainbow where sensibly possible… Then again, your greens are definitely your best colour.
I notice your bench pic doesn’t show BT’s costume - do any others have costumes?
Starting with tank:
Boldtusk can manage it, but with even with costume bonus and lots of emblems, he’s not going to cut it with the better 5* tanks… And you’ve got a couple of those.
Obviously Guin isn’t the meta trendsetter she was but she’s still very capable (but not maxed so irrelevant).
But the new Queen on the block is a monster tank too - Alfrike may be very slow, but she deals significant damage with mana control.
I’d definitely try setting up an Alfrike defence - if you can swing more emblems her way, I’d certainly do it (personally, I’d reset Kashhrek in a flash!)
Both Kadilen and Lianna can flank pretty well - Kadilen’s special is more defensive, giving you defence against special skills whereas Lianna has real killer punch… Lianna is more often used at wing, whereas Kadilen is much better at flank than wing.
If a healer is going to sit well anywhere it’s at flank - at wing, they usually fire too late to have much effect.
I’d seriously consider moving Boldtusk to flank, and with attack boost BT usually goes on the left.
Boril actually sits pretty well at flank… And almost necessitates a dispeller on attack.
Sonya with all those emblems has defence beef and she’s still fast… And gives you that useful left wing dispel. She’s not a killer sniper, but she’ll survive well - if you have costume (bonus, still use regular form) this would be even better.
Chao is fast and cuts mana (and you’ve got plenty of emblems there) but again isn’t a killer sniper.
Doubling up the greens… Running Lianna at wing (opposite side to Kadilen at flank) gives that punchy killer-sniper wing that can win a battle late on… It does mean running flanks in the opposite order, or running Sonya on the right.
Double Lianna wings… This is a braver one as it means either running Sonya at flank (dispel) or running a defence without dispel, with Boril at flank.
So… A couple of possible setups to run and see how it works:
Sonya - Kadilen - Alfrike - Boldtusk - Lianna
Lianna - Boldtusk - Alfrike - Boril - Lianna
Lianna - Sonya - Alfrike - Boldtusk - Lianna
Sonya - Boldtusk - Alfrike - Kadilen - Chao
Basically… You’ll have to try it and see - it’ll usually become obvious which is working best.
Or perhaps that several are working well enough to do the job, in which case it won’t matter which you use.