Is regularity is preserved under reversal? When talking about languages and regular languages. Can I say that reversal preserved regularity since if the language L is regular, we can generate it by right linear grammar. Therefore, the reversal language will be the left linear grammar version of L. Is that true to say?

yes it is regular, to prove this, for any regular language, L, you can find a DFA and by reversing the transitions in the DFA you will get another DFA that accepts the reverse of L.