Yeah, the whole "subscribe to events then check a status result" thing is pretty bad. This is compounded by "Box" behaving differently than everything else. When I made JxlSharp (C# JXL library wrapper), I had to add a workaround in there to force Box to behave like all the other event subscriptions.

And buffer sizes aren't handled in a good way. You have to provide pre-allocated memory, guessing how big it is supposed to be. Then you get a "not big enough" error. This is a guessing game, not a good design. You're forced to overshoot, then shrink the buffer afterwards.

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In different APIs, there tends to be a function you call to get the required buffer size. For example, many Win32 API functions make you call them with a buffer size of 0, then you get the actual required size back. Another possibility is having the library allocate the memory, and return the allocated buffer to you. Since cross-module memory management is hairy (different `malloc` implementations can't interoperate), some APIs let you provide the `malloc`, `realloc`, and `free` functions.