I've seen individual wrong trees at least a dozen to twenty times every time I've played this level, compared to maybe ten times total on all other levels combined, across over 650 hours playing Eufloria according to Steam

. Three out of a total four times playing this level, I have seen one asteroid have every tree on it belong to the wrong player, which causes the game issues I described originally. An asteroid can have one, two, or three incorrect trees on it, but significant consequences only occur when all three are incorrect.
One of the two possible cases (friendly planet with three enemy trees) makes it easier to win since the enemy keeps sending seeds to an asteroid he cannot conquer. Even though your allied AI keeps sending seedlings to their doom against vastly superior enemy numbers on that asteroid, it is only a part of your total force. So you can bide your time carefully using the laser mine to hover just outside the attack range of the enemy seedlings orbiting that asteroid to slowly reduce their numbers. Meanwhile, your own forces gather strength to the point where when you finally get rid of all the seedlings on the buggy asteroid, you have enough to overcome the ferocious late-game super seedling counterattack.
The other possible case (enemy planet with three friendly trees) is impossible to win since the reverse is true--you can never conquer that asteroid since your seeds won't attack a friendly tree.
My experience has been that without case #1, the level becomes so hard once the super seedling counterattack gains steam that it's not so much fun
