Make T-based validation warning on Statements more specific

[davidzbiral]

Now, the validation says what entity it concerns, but does not help in knowing what validation rule makes the statement invalid:

Thus, help the user by saying what the rule is, incl. listing these things from the data validation protocol as entity tags. E.g. here, the 3 statements are not classified as C trial statement or C non-trial statement, and the user needs to know what exactly is invalid.