Also we have music in the Dnc questline that is from FFIX.

Surprisingly FFIX has more representation than both FFIV and FFX (I say this due to popularity and sales figures)in this game at this point of posting.

5.4 spoiler you are warned

Though with newest MSQ looking to be a few FFIV re-releases entities showing up in name, making FFII as the least represented numbered final fantasy in FFXIV having only 1 outfit and a password used in ARR msq.