I'd say just make as much of the content editable via pull request as is feasible, starting with the pages leading from the Learning tab. Now that you have the Language Reference system in place it should be quite easy to extend that to the rest of the documentation content.
It may take some work to set this up but I think it will very much be worthwhile in the long run. The thing is there is a lot of room for improvement in the documentation and good documentation is so important for the target Arduino user. I can find issues on almost every single page. I understand, it's a lot of content and typos happen but it doesn't need to stay that way. The Arduino community is a huge resource but you need to efficiently tap into that resource. A lot of people will not act on issues they spot in the documentation unless you make it easy for them. There have been bad feelings in the community related to long-standing issues with the documentation. When they report these issues on the forum (as they are told to do), nothing happens because nobody with the power to make the edits bothers to read the forum. In fact the link even takes them to the wrong forum section (
https://github.com/arduino/Arduino/issues/6526)! Making effective use of the community is even more important now that the documentation translation project is under way. The new Language Reference with the Edit button is such a huge improvement and shows great vision. I really think the system can serve as a model for other open source projects. Kudos to the people involved in making that happen!
I suppose the product pages might use a different system but they are also documentation and I have found quite a few typos and errors on those pages. I have submitted issue reports to the arduino/arduino repository for some of these but the latest (4 months ago) ones have not been acted on so I have felt that it's not worth my time to put more energy in that direction, even though I have a long list of additional issues I could report. I think part of the reason for that is they get buried in the arduino/Arduino issue tracker where they are not even really on topic. It's really inefficient for me to manually generate a diff for the edits and then for the Arduino team member to make those changes, rather than a pull request when I could directly edit the content and the repository maintainer could just review the changes and hit the Merge button. So here you have an example of a potential volunteer anxious to work for free but unable to do so. If it's not easy to extend the documentation editing system to the product pages I have an alternate suggestion: Move the bulk of the board documentation out of the product pages and into the standard documentation system, then just link to that content from the product pages. The product page would simply contain the sales pitch for the board and link to the board documentation page for the rest of the info. This would also be linked in to the Getting Started pages for each board.
After that, what remains of the website content is what I'd call infrastructure. Things like the home page, store pages, contact page, etc. Some of that content has issues also but my primary concern is with the documentation. We can continue to use the old inefficient system for the rest.