Deprecated message groups
Wikidocumentaries seem to be no longer available, so it should not be listed for translation. The same for iNaturalist, which has moved to Crowdin. This should be made clear to translators so that work is not done in vain.
Wikidocumentaries is not discontinued, but it has unfortunately been down for a long time because of the unavailability of our only developer. Please do not kill it here!
Thank you for you patience!
As far as I can see, iNaturalist is not listed as a project for translation. Old messages and translations are usually kept here because they may be useful for translation memory, but you are not supposed to see them in the translation interface at all, and you only find them if you really dig for them. If you do see it anywhere as a project for translation, please let us know.
I'm not sure about the status of Wikidocumentaries. I can try pinging its maintainer.
That would be great. iNaturalist mostly occurs in sets of translations with the same content.
If by "sets of translations with the same content" you mean translation memory suggestions, which appear in the sidebar, then yes, they are kept, and this is more or less the intention. (Nike can correct me if I'm wrong.)
If you think that it's a problem, it can be discussed. I think that it's mostly useful. Occasionally, I even edit iNaturalist translations into Hebrew if they look wrong to me even though they probably won't be used by iNaturalist, because I want the translation memory to be correct and useful.
I mean Template:Identical (e.g. ). Translation memory is only given in selected languages (Special:Preferences#mw-prefsection-editing) and depends on the message group. I agree iNaturalist messages should be kept and may be useful for further reference so I also translate them. On the other hand, I'm glad to note iNaturalist is not included in Special:LanguageStats anymore as I have already translated it once (on Crowdin). As to Wikidocumentaries, I would be glad to translate the messages but as far as the status remains unclear, I'm leaving this for later when more active projects get translated.