Backend: input with variable does not respect input type:

Update - this issue is tracked in #438723 and #434826 (closed)

Problem

With the introduction of expand_vars users should be able to use variable + input anywhere, however this does not support any key that is not string, when you try to add parallel: (number) or allow_failure: (boolean) I am receiving the following error When I try to force the type using type: boolean/number I receive a different error

Its important to note that I did not saw this problem on keys that are type of string (changes: or when:)