Rough TL:

(alternating yellow text) pow pow

(yellow んも~~~!!) grrr jeez!

(yellow バカ~~!!) baka!

(purple んも~~~!!) grrr jeez!

(purple ち~が~う~!!) stupid!

(purple ちがうてばぁ~~!!) stuuuupid!

Basically she's just mad and making sure you know it.

Right side of cape: "Jeesh!"

Left side of cape: "You're late!"

ちがう means "you're wrong!" or "it's different than that!" or "it's not what you think!" not "stupid!"

In this context it could also mean "you promised!" as in "this is different than what you promised!" or "you promised [you would be here on time, and you weren't]!"

I'll amend the translation:

(alternating yellow text) pow pow

(yellow んも~~~!!) Nnnnaaaargh~~~!
(yellow バカ~~!!) Stupid~~!

(purple んも~~~!!) Nnnnaaaargh~~~!
(purple ち~が~う~!!) You~ pro~mised~!!

(purple ちがうてばぁ~~!!) You promised, you jeeerk~~!!

Right side of cape: （んもー もっとー） "Nnnaaaargh! You're even more-" Left side of cape: (おそーでよー）"late this time!"

Vid-szhite said:

Right side of cape: （んもー もっとー） "Nnnaaaargh! You're even more-" Left side of cape: (おそーでよー）"late this time!"

Actually, it appears to say んもー　もっと　あそんでよー, "Nnnnargh, hang out with me more!"

Sumi's form of “offense” when sad.