I have this problem with my website. As I started the current project, about a year ago, I added 3 more languages besides English.
I used Polylang. That is, editable by hand, each language can look like a completely different page, etc.... Not automatic.
However, the first few months I was able to update pages in other languages. However, it's getting worse with time. I changed the design of the site, graphics, adds new sub-pages in English. And those pages in other languages stopped in time. I just don't have time to update them. Especially 3.
And my question is, what to do about it? if I delete so many pages, won't it have a negative effect on the site? Or can I leave them on the site and come back to them I don't know in six months when there is time.
These pages are mostly indexed and account for about 10-15% of organic traffic to the site.