Can Testing Cheats really damage your game?

I've played TSM with testingcheats on for about 460 hours. I can't say I've noticed anything buggy (except the known bugs in the game, of course). I use it for maxing out friendships, primarily, because the friend requirements for quests is ridiculous and annoying.

@Sindocat I didn't know we could decorate the forest entrance and town square? Is that a shift-click option in those locations? Always felt those areas were lacking.