We kept the old data for ~1.5 years after 6.7 became the LTS, then dropped it because maintaining it does impose a burden.
You may be able to deduce the correct versions by looking at the individual plugins’ release histories and choosing a version released around (just after) the date of the initial 5.6 release, which you can see here if you “Show all versions”.
That said, I can make a few comments about individual plugins:
- clover - this plugin is no longer maintained. You’ll do best to just rip off the bandaid and switch to JaCoCo
- cobertura - ditto
- css - the one you were using was provided by a community member who took his toys and went home. A SonarSource-maintained analyzer is available for 6.7 (but I think not embedded). Maybe just leave this out until you get to 6.7 and then you can install the latest
- java - the correct version will be embedded with the platform
- l10n-fr - this isn’t under heavy maintenance but AFAIK not incompatible. You can probably just upgrade to the latest version, 1.15.1, and be fine
- ldap - go for the latest version. I’ve checked compatibility, and it will be fine
- pdfreport - this stops working at some point. Honestly I forget the details, but best to just drop it now IMO
- web, xml - ditto java, I believe
Good luck on your journey!