H1 - never fold this river. Like philly said he canhave worse jacks he doesn't really know what to do with and yeah shit like TT random pairs and even bluffs. Yes it's only 20 hands but I rarely run 60/55 over 20 hands, so it is somewhat likely he's a loose tard, this is also enforced by his river sizing. We're good closer to 50% of the time nevermind 25%.

H2 - Meh I'm okay with preflop, I'd go ahead and fold river here, his sizing is actually scarier here and all you have is a bluff catcher. The problem with having a bluff catcher here is that a lot of his range has at least some sd value, like Tx 9x, most Ks and Js he's likely opening. even shit like 66-99 he might not feel like he needs to bluff with. The only combos of bluffs are like suited middling cards and baby pairs, defo not enough of these to call river.