How odd, I checked and that particular error should be triggered when the inflated size of the archive exceeds 500MB. Could you tell me how big the archive is when unpacked? Once I know the rough conditions I will try to reproduce the issue myself.
It's definitely something we want to resolve sooner rather than later. Unfortunately it's frustratingly awkward to implement, and the requirements for the feature are definitely not what I would call "clean". But, at least if we implemented it would be out of sight so devs don't have to do much extra.
I've looked into alternative methods that are probably somewhat similar to what your doing; where a server holds an asset pack that the runtime downloads and loads assets from. It's actually fairly close to expansion APKs, and I expect quite a few games on the store actually do this. The downside is that if a user downloads a game, then runs it for the first time offline, it doesn't work. Expansion APKs don't actually guarantee to download when the user installs the game, so this can still happen with the "official" method frustratingly.