No idea if the crowns thing code got fixed in the www-internal website code, but be aware of this:
viewtopic.php?t=9592-warning-practising ... our-crowns
viewtopic.php?t=9614-www-internal-duoli ... e-progress
There was another thread:
viewtopic.php?t=9759-internal-duolingo- ... increasing
Hard to say what limitations you might run into.
I have to at least say that my German reverse has some web vs mobile app synchronization issues when I tested out 2+ checkpoints in my tree on that www-internal website and the app doesn't show completed L1 skills, one CP is now shown as finished, another as half finished (Practice option, but no correct colouring) and the owl is missing on the mobile app.
I mean you can try the Skill Practice Urls, but don't be disappointed if the crowns count is different afterwards.
My PT mobile app progress (old version) seems to be reflected correctly on the www-internal website.
But I need to try higher crowns first to tell how reliable their data is as the new path/snake doesn't support 5-6 crown levels anymore.