First option is to switch them around. It wouldn't hurt to read "the Gray Gandalf" or "of Isengard, Blekblug." You may put a comma after last names just like on some official forms - last name, first name.

Another option is to use the same 'forename' so when they're assigned title they don't look weird. The hard part is figuring out that same 'forename' lol. Well, you know, you can try translate anything to blank though I haven't tested this myself.

Forenames:
["Blank"]
{""}

Surnames:
["Revenant"]
{"Revenant"}

["NodachiSam"]
{"NodachiSam"}

When "blank Revenant" and "blankNodachiSam" are assigned titles they would look like "Lord Revenant" and "Lord NodachiSam."

Good Luck.