We're not going to make a feature that caters to a specific language only, end of discussion there. If we were, I'd make it apply to Finnish only just to spite people.
I could imagine this could be maintained as a curated list in v5, maybe, but overall this is definitely not a thought-out suggestion and I've rejected it numerous times for a reason. You do realize that if the END chapter was the only necessary component, trolls would have even more incentive to release the final chapters of every series where the scanlation lags behind.
"Then check that there's no gaps also," you might protest. Not only may a series have legitimate gaps, that just gets even more complicated to account for, and we'd have to start implementing features that we're explicitly planning for v5 because they were too big to start retrofitting into the current site.