Remove Overlap (⌘⇧O) seems to resign at large coordinates around 7000 em.
I use Glyphs as a vector tool copying paths from and to Illustrator (…). My „glyph“ has a width of >30,000 units at font UPM height of 4,000. The more left parts accept and do the remove overlap, while the more right parts cause an error message.
That is a known limitation of the remove overlap code form Adobe. Can you try the remove overlap from the transformation panel. It used a different algorithm.
Good to know. That works. Thanks!