Thanks for letting me know that events aren't supported.
Since the import order is the same as in MNE, I was able to make a Brainstorm script that would add multiple tags from a csv file with the column 'label' and a row for each epoch event.
I'll share it for anyone else who has the same issue, but it's literally just a bastardized version of 'Add Tag' that I duplicated and tweaked slightly:
process_tag_by_events.m (6.5 KB)