In the future if you have any matchup inquiries, just post them here. Helps keep the forum from being cluttered.
That aside, I think this matchup is definitely one of the harder ones for Rose. Throwing Sparks is out of the question most of the time because Blanka can easily punish fireballs with slide or his forward ball. Rose doesn’t have an answer to continuous electricity pressure (she can backdash any followups however). Blanka has solid pokes and anti-airs and his jump-arc can make him pretty difficult to anti-air too.
Blanka doesn’t have any reversal options without meter so feel free to pressure him with meaties. Even when he does have meter though, his reversals aren’t hugely damaging but you should watch out for them nonetheless.
I prefer using Ultra 1 in this matchup because I want to punish Blanka hard. Similar to Soul Piede, it’ll catch pretty much everything but properly spaced forward balls. You usually should be able to punish blocked EX Upball with cr.MP xx Spiral, maybe cr.HP xx Spiral. Punish EX Rainbow Ball with FA. If Blanka crosses up, then just dash out of it and if he hits you from the front, let it rip. Don’t use FA if Blanka does EX Rainbow Ball as a reversal however as it will break armor.
If Blanka decides to go for hop shenanigans, just use cr.LP to hit him out of them. Do the same thing if Blanka throws out a lot of forward balls.