I agree with most of what you wrote and I think that ParserComp 2022 was close to perfect. Actually so much, that I think it would be a shame to take ParserComp away from itch.io as it is a great place to share interactive fiction where people from other game genres might (re)discover interactive fiction/text adventures. Of course, if you think itch.io is too unreliable I understand, but if you learned something so you can avoid the technical problems next year, it might be worth considering Itch again?
I think it is perfectly fine that you avoid the (in my opinion unfair) default score calculation on itch and I don't think it is a problem that it takes a few days before the results are shown. Perhaps you could just alter the top of the main page by adding a single line like: "The ratings are being processed, come back in a few days to see the results." or something like that but that was not a big issue.
To sum up: If you just avoid the technical glitches with ratings we had this year, I think you already have a great competition. And as the problems got fixed, it wasn't a big problem anyway.