Sorry, I should have mentioned:
The last warning has been fixed on the 3.8-beta branch only. It will not be integrated in 3.7 since the changes would break the API. Spine 3.8 will be relased in the near future.
I will disable this warning on 3.7 via a #pragma statement for convenience.
I have just released a new 3.7 unitypackage with the warning suppressed, you can download it here as usual:
Spine Unity Download