Seems like it, though it wasn't actually my intention. I'm not even (planning on) using my Mastodon account much. But when I followed the MassisvelyOP account on Mastodon they followed back and I thought, I should (at least) pin a post to my Mastodon profile which references our GW2 community.

What I didn't know until now is that referencing a lemmy community from Mastodon also creates a post in the referenced community. I thought that you could only comment on lemmy posts from Mastodon.

But it appears that only direct replies to the post (comments on top leveL) are federated back to Mastodon. Replies to comments (nested comments) aren't shown when expanding the post.