actually it is , since Gai use Goken , which is a punch with strength , and CES is Chakra enhanced strength ,depends on the fact that can sakura get out of suiton via superstrength if she gets trapped becoz as you said she has zero knowledge about mei's ninjutsu so i can see her getting caught in her large scale suitons
i do remember base gai's punch being ineffective on water prison against kisame but its not good comparision
but I guess you have a point , since CES is much stronger , and Sakura was able to bounce this
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I can't see why she shouldn't be able to bounce Mei's suiton techniques