Yes it is hard.
I searched Titles of Catholic Clergy and found this TIA page.
https://www.traditioninaction.org/religious/d003rpHowToAddressClergy.html
And with the first one, about deacons, it was different at SSPX seminary:
Deacons
Direct address: Deacon Morris
Written address: Reverend Deacon Michael Morris
Formal introduction: The Reverend Deacon Michael Morris
At St. Thomas Aquinas Seminary, it was "Reverent Mr. Morris". And, to make it even more confusing, the French (and there was a French presence there) addressed Deacons already as "Abbe" (= "Father"). I understand that the expression for priest is also Father, but with a different word, "mon Pere" or even "Monsieur l'Abbe", so just a "Monsieur" in front of "Father".
So Europeans commonly refer to Bishops as "Monsignor" whereas in the US "Monsignor" is an honorific title for an older or more prestigious priest (bestowed by the Church).
So if you're a Traditional Catholic, you first need to figure out if they're from Europe (which commonly happens) and THEN figure out which of the titles available in each language one should use.