This is on the Zotero side in their MODS importer. I didn't poke around too much but found:
1. The last /mods/titleInfo/title is imported into the Title field. In the example below, the second [type@='alternate'] is imported in Zotero; the real title isn't imported at all.
2. /mods/typeOfResource and /mods/genre don't seem to import; all MODS items from Aquifer seem to get imported as a "Book".
3. /mods/originInfo/dateIssued does not import at all.