https://draftable.com/compare https://draftable.com/compare is by far the best solution I've found for this, and it's a shame it's not more widely known about.

https://draftable.com/compare https://draftable.com/compare is by far the best solution I've found for this, and it's a shame it's not more widely known about. It's not open-source, and their offline app is Windows only, but its ability to handle multi-page relayouts is far and above Acrobat's diff functionality (as the OP laments), and there's a free online version that's reasonably secure so long as you don't share the secret URL around. I've used it many times to obtain readable redlines when only given successive "baked" versions of a document, and it's a really useful tool for any B2B startup founder.