If they're bugs, they shouldn't be left in. Ever. You're trying to make your game artificially challenging, which is a bad-faith move. If you want your game to be hard, do it with challenging level design. Saying you "left the bugs in deliberately to make the game more difficult" is a fancy way of saying "I suck at programming, so I'll say it's intentional and hope nobody calls me on it."
Get better at making games, then submit them.