Wouldn't that be bad in next episode, if he is still under 50?
Possibly, but unless he gets a big story boost to happiness, it might not be possible to get him above 50 unless you 4-dot him in both Episode 11 and Episode 12.
My Tremolo started at 11% Happiness, so I'll need 39 points minimum to get 50. Alcohol and Food gives a 3% happiness boost to him and the Wet T-shirt contest gives another 2%, so let's say 34% remaining from Needs (and whatever Activities come in Episode 12).
Excluding perks like Easy to Please, getting 3 Needs is a 10 points boost and getting 4 Needs is an 24 points boost. You get 14 points and 29 points respectively with Easy to Please. So at a minimum I'd need to 3-dot once and 4-dot once, which would bring me
exactly to 50% without Easy to Please or 59% with it (before activities and other adjustments in Episode 12).
Edit: On that note, I actually kind of wonder if Tremolo's starting happiness might be a bit bugged due to "swapping" positions with Nick. None of the other DIKs started anywhere near that low (their starting range is randomly chosen between 35-45). We'll see if that eventually gets changed or not.