These were uncovered when porting the mangling tests in ms-templates.cpp from clang/CodeGenCXX over to demangling tests. The main issues fixed here are surrounding integer literal signed and unsignedness, empty array dimensions, and pointer and reference non-type template parameters.
I'm on Linux right now so I can't run these through undname to check what it returns in these cases, but I'm satisfied with our output regardless and it matches up with the original source code.
I'd like to eventually do something "prettier" for the uuid cases, but for now at least it's not wrong.