Hi jan9368,
Revel does, indeed, see tags from PSE. PSE doesn't actually put the tags in the files (it's PSE metadata) unless the user specifies to write the keywords to the files (it's a separate command in PSE). Revel will acknowledge any tags applied to the files themselves actually. One possible reason the keywords may not appear is that you may not have applied the keywords to the files. It's dangerous for PSE users to NOT save their keywords to their files because if they loose their PSE catalog they loose ALL the tagging they have ever done.
There are a few special Elements-only tags of which Revel can only see "People and Places"
I hope that helps.
Best regards,
Glenyse