I previously had a personal vmdk MB server and haven’t used it in years I still have my music library to tag and in 2016 Picard (Win) was only capable of tagging at max 2-3 files at a time. Has this limitation been removed for those who run personal MB servers?
Here, an old ticket:
https://tickets.metabrainz.org/browse/PICARD-784
https://tickets.metabrainz.org/browse/MBH-31?jql=text%20~%20"rate%20limit"
Not sure what you mean, do you mean the rate limiting and requests to your private instance? The rate limiting has been overhauled completely, but the default is still 1 request per second with exceptions for AcoustId and Cover Art Archive.
You can customize these limits using a simple plugin, but the code for this changed quite a lot recently, I have to look up how it works in the current stable release.