Wow, faster than I thought :-) Thanks for the feedback! I'll think about it. Although, I try not to spoil what's in there... but you are spot on - yes, the house (and some other places), was a kind of forced decision provided some states can get mixed and keeping them dynamic would increase rules and that will lead to slowing things down even more (there was a difficulty with speed provided map size, which was partially solved with some tricks). Not that it is not doable, but it was a part of laziness, a part of over-complication this 'little' things will add to the code, and a part of 'it cannot go on forever, make a cut!'. So, I guess, it turned out to be a part of the package...
And about 2 more 'things' to find - honestly, it's impressive you've found almost all, as few of them are a little nasty (almost NES type of nasty) to find. But there are some clues in the environment (some 'extra' elements might betray them, the nastiest one is probably in areas connected with water, but not saying anything else :-) ) and it was the initial plan ;-)
Have a nice adventure!