This covers several different things, but since they all affect each other, I'm not sure how best to split it up.
Now that we have proper series, I think we should revisit the guidelines we have for them and consider which bits it makes sense to keep and which bits are unnecessary now that we have series.
e.g. If people want to have completely standardised titles, we have enough data for people to create one using the series name and series number, so there is less need to standardise things like release titles too.
A few of the things I'd really like to see addressed:
The guidelines currently allow any word to be used instead of "volume"... as long as it's not an abbreviation. This doesn't make any sense to me - how is a series consistently using "Vol." any different from a series consistently using "Edition"? I think it would make more sense for the abbreviation guidelines to instead say that when it's not clear which to use (i.e. if both the abbreviated form and the unabbreviated form are used), we prefer the unabbreviated word, but to otherwise allow abbreviations if that's what's used.
Using a comma to separate the title and volume number is unnatural for some writing systems. It works for a lot of languages, but it really jars in Japanese because Japanese does not use a comma in that way. Chinese also doesn't use commas like that, as far as I'm aware. Languages using the Arabic script might, but they have their own Arabic comma which would probably be expected instead of the ASCII one.
The series, volume and part guidelines are all very similar. I think it would be better to have one guideline that covers them all which mentions any specifics which only apply to certain things (if there even are any).