Errors at installation time should be fully diagnosable, and even if the output today
doesn't make it totally obvious what happened, it would be easy to fix in rpm.
The errors post-install are a bit trickier. Imagine you install your rpm, and kick off
some long running daemon from it. A month later, a block gets corrupted in a way fs
checksums don't catch (e.g. ext4, btrfs nodatasum, evil maid), and suddenly that
daemon receives a SIGBUS and crashes. You would be able to see clearly that it was a
verity issue in dmesg, but I don't think the binary could reasonably know what
happened or write a meaningful log. In that sense, I think it's actually pretty
similar to the experience if you have corruption in your disk and start getting btrfs
checksum errors on a file--you'd have to look in dmesg to know why your file is
broken.
The middle ground is when opening/exec-ing the file fails. In that case, you might get a
sufficiently specific error code you could figure out it's verity, and the full error
would be in dmesg as well.