I imagine that you know that the new version, etm-dgraham on PyPi, has a GUI based upon the python prompt-toolkit and runs in a terminal window - not QT but still pretty nice I think. My emphasis in developing this version has been on functionality rather than form. There are, of course, many more up to date calendar apps. Fantastical is an example and one of my favorites and I would be using it myself but for the fact that it doesn’t have some of the functionality that I most want.
I’ve spent much of the last two years working on the new version and am pleased with the outcome since it satisfies my needs almost perfectly. I’m not sure how many users I have for the new version, but I’ve gotten so little feedback that I suspect it’s not many. I imagine that a port to QT would take another couple of years and since I doubt the result would compete for look and feel with apps like Fantastical that are supported by teams of programmers and designers, I doubt I would gain many new users. All things considered, my motivation to take this on is currently not strong.