They need to find a way to detect XIV Alexander and ban people

[GayRobot]

They could use nProtect GameGuard like PSO2, if it detects any 3rd party program running that the game devs dont like it gives you Error 1013 and force you to close the game, crashes the game or gives BSOD. If that's not enough, implement checksum file that the game checks and updates regularly while you're online.
In PSO2 if the devs find people using parser they ban accounts without warning for cheating.

I guess the anti parser people would be happy.

I made OverParse, a damage-log viewer for PSO2 JP. When it got blacklisted by GameGuard, a friend and I played cat and mouse for less than a week, then found a complete bypass that worked in under 10 lines of code. Years later, it still runs fine, and I have never heard of anyone being banned for using it without first making a fool of themselves posting damage logs on social media—much like FFXIV.

Client-side anticheat is rarely a serious impediment to cheaters; there are plenty of actual cheats for all versions of PSO2, the walk-through-walls infinite-PP kind, that still work just fine.