I found a post by KevinCow that seems to address, albeit indirectly, most of my questions, and would like to quote the relevant sections here.
. . . “You're right that I don't have deadlines, but I still have limited energy. I've been working on this game that I can't monetize for nearly a year, and I'm kinda burned out. I need to finish it up.”
[. . .]
“And since the next update will be the last, with a Kiara level and Calli boss fight, this level would give Gura at least some stage representation.”
(KevinCow, 2021, https://itch.io/post/4465579)