If you have custom units with modified models and portraits, you'll need to check their model and portrait paths - 2.0 made them separate fields. So now custom units with modified models use original portraits by default.
Luckily, you only need to do this once per campaign file (and once per map if there are separate custom units there).
You may have to check if you use any core assets that were deleted between 1.31 and 1.32 (they could be deleted earlier, but I have no specific info about it). If those are critical - they can be found on Hive and imported. One-time issue.
If you only want your maps to be played in SD (classic) graphics, check that it is set so in map options for every map. One-time issue.
If you want your maps to be played in HD, note that if you have a custom object with standard model/icon/effect, and user uses SD+ setting for corresponding objects (plays in HD with "SD" assets), these custom objects will always use HD assets. The only way to bypass it is to mod the game - editor has no way to add an asset as an SD+ option.
Usual heroes will use selected multiplayer model and voicelines, if their model is not modified. You either have to set a different path to a model or make a custom unit - they ignore collection skins.
Triggers shouldn't be affected. There may be issues with core game AI, but I don't know much about it.