Re: Operators on ranges with a domain subtype do not implicitly cast operands of the domain's base type

I hit what looks to be the same issue. I reported in here:

David Johnston said that he thought that it was a bug.

My workaround is to typecast the two operands explicitly back to their base types.

I don't think that there's any magic to fix it declaratively. My guess is that you might work around it with a user-defined operator for the domains in question that hides the typecasts in its implementation function. (This has worked for me in other cases for other reasons. But I didn't try that in my testcase.)