Nope, he hasn't returned to work on GBH yet. The screenshots and animations he's put out are mainly done for fun and to test out stuff (like a different hair for the hero) that could make development easier for him.
Now that you mention it, recently it's been hard to keep track of what Boko is up to. I looked back at his tweets to refresh my memory, so here's a summary...
- Pre-August 12: Worked on UFG2.
- August 12: Decided to take a break to refresh himself, but said he'll probably release some small stuff (as in, screenshots/animations on Twitter) for fun.
- August 21: Mentions that he tried out RPG Maker MZ, and it's a little better but not significantly different than the version of RPG Maker he currently works with for GBH. He said it'd be easier to develop GBH if he could make his own plugin or modify someone else's, but he hasn't been able to find the time to learn how.
- September 10: Decided to pause development of UFG2 and study how to create motions and tweak character models. No detailed explanation of his intentions yet. But my impression is that once he's done with this, he'll just return to UFG2 rather than GBH.
However, you can tell from his tweets that he GBH continues to be source of creative energy for him, so I'm looking forward to what we'll see when he finally returns to GBH... though I don't expect that to happen for months.