For which we are very grateful! 
There are a couple of locations for plugins:
- Our default plugins, inside the enigma2 repository (develop, rc and release versions, merged when enigma2 itself is merged)
- Our own plugins, inside our enigma2-pliplugins repository, only one version
- Imported plugins maintained by OpenPLi, inside our enigma2-plugins repository, only one version
- E2Openplugins, separate organisation on github with plugins maintained by third parties, only one version
For the last three, these are "oinned" in the build on commit hash in rc and release. The reason for this is that as they are developed, they may contain dependencies on the develop version of Enigma2 which are not present in the rc or a release. We rely on the developers to let us know if a pinning can be safely changed so the plugin can be updated in rc or release, but unfortunately this seldom happens.
The same is true for a translation, as that generates a new commit in the plugin, which means the pinning in the rc and release build needs to be manually updated.
Ideally the developer or translator also sends us a PR on the reporefs.conf file (containing all these hashes) when that happens, but in practice we have to sort that out ourselfs, which is quite a bit of work, and therefore doesn't happen that often.
Currently in use: VU+ Duo 4K (2xFBC S2), VU+ Solo 4K (1xFBC S2), uClan Usytm 4K Ultimate (S2+T2), Octagon SF8008 (S2+T2), Zgemma H9.2H (S2+T2)
Due to my bad health, I will not be very active at times and may be slow to respond. I will not read the forum or PM on a regular basis.
Many answers to your question can be found in our new and improved wiki.
