So far the Unity plugin side has been pretty lightweight but there's more C# and better integration in the works.
Most times, updating just Everyplay.framework is sufficient since there are no graphics changes in the plugin. With 1.7.6, there's a transition going on to a new graphics integration, which is used by default when compiling against recent enough SDK, otherwise
it's falling back to old integration.
So it's important to know if the latest plugin has also been re-imported to the project
and in some cases graphics bugs are bound to be Unity version specific (version info missing)
Please feel free to send more information or potential test case triggering the issue to support at everyplay com
UPDATE:
It seems both 1.7.5/1.7.6 SDK's using the new graphics integration used in the latest Unity package have a regression when dealing with custom sizes through Screen.SetResolution().
This has been fixed to the next release following 1.7.6, thanks!
As a workaround, keep the device resolution as native or modify
Assets/Plugins/iOS/EveryplayGlesSupport.mm
to always build with
ENABLE_GLES_WRAPPER
enabled