Unfortunately Real48 does not have any type info.
You can see that when you try compile this:
program Project1;
begin
TypeInfo(Real48);
end.
The same goes for the string[n] syntax. But there you could probably fix it by defining your own string types like:
type
string30 = string[30];
That alone would not include the rtti for the record field so you need to hack/fix the rtti as I showed here: https://stackoverflow.com/a/12687747/587106