I had a similar issue recently involving asIScriptFunction::GetDeclaration. While personally I certainly don't mind it explicitly stating the global namespace, it appeared as if asIScriptModule::GetFunctionByDecl was unable to interpret it. That means that neither including nor omitting the namespace always allows for identification of a function. Additionally, in this case the redundant "::" could prove more difficult to find and remove if one were to do that by hand, because it doesn't directly precede the string (and there could potentially be more occurrences of it, e.g. consider "foo::bar ::function(foo::bar)"). What I ended up doing was
asFunction->GetDeclaration(true, asFunction->GetNamespace() != '\0', false)
which, honestly, looks like a terrible hack, but works. Either way, if not getting rid of the explicit preceding scope resolution operator, I would suggest at least modifying GetFunctionByDecl and possibly other similar functions accordingly, as they should most certainly be able to interpret declarations returned by other library functions.