Do not use retail FFXI for nasomi.
There is no way for you to get the "exact" same ashita version that nasomi uses without using the nasomi installer.
That fix it's to play Nasomi or Retail , not both at same time, if im not wrong.
Nas uses Ashita 2 version 18.104.22.168. And you can actually download that version.I knwo he have capped addons etc, it's a custom Ashita, but it's runing on that version.
What im really asking is if is allowed, cause i am currently playing both just fine, no errors or anything. I saw here searching on forums that some peopple use this method also to play both at same time, and i can't find "exactly" any rule about not permiting this
Tbh this shouldnt be a problem till Nas fixes the launcher, since there is no way to actually play retail+Nas at same time, and many ppl use to play both