My trident produced a few miniscule leaves (even smaller than the smallest leaf in the series, but not typical for even the most refined trident maple bonsai) that were the tree's final attempt at new growth at the tips of a few branches just as the temperatures became too low for growth and then turned cold.
Japanese maple (the species) reduce pretty well, but nothing like trident maple.
Need to get a chinese elm from a more northern grower. I bet some are could be wintered similarly to the above maples and do well.