Would "Dumber" work as a translation for "Twpach" as "Stupider" doesn't feel like the word people use in this situation.
I wouldn't really ever say "dumber", this is probably just another regional thing.
I'd say it's probably more American than British as that's where my English is from, America. :) I was just inquiring about whether or not dumber shouldn't also work, is all.
I see in the hints that 'stupider' is accepted here, although rejected a few moments ago in another exercise! Weird! Also, for our American friends, dumber would be their word of choice!