I believe that they stated their intended stopping point is level 15 for Besieged. At least for now, I guess. Level 15 Besieged will put it at iLvl 119, if I recall correctly.
For what it's worth, I only recall them saying they were raising besieged to 99 and then to ilevel. Which technically, they've already done.
Do you know where they spoke specifically about level 15 or ilvl 119?
Having trouble finding it on Google but I believe it was stated that 119 was the target during the Freshly Picked Vanadiel on May 10th last year. They specifically stated that they would not push to 119 all at once but rather in steps.
I think the level 15 was shared in another Freshly Picked later last year, too?
Edit: I found the translation of the May Freshly Picked - ironically, you were the one who linked the translation in this very thread back on May 12, 2024:
"Making Beseiged Level 99 Content:
This content is currently made for LV75, and work is being done to adjust this first to LV99. They can't skip straight to LV119, but hope that players will participate in order to help rescue important NPCs. The goal is to make Beseiged more challenging (like it used to be), but also manageable, which is why it will be balanced for LV99 as opposed to LV119. The strength of the Serpent Generals will also be increased."
I do acknowledge that this leaves it open to possibly not be a 119 target but stating that they can't skip straight to 119 seems to imply it, in my opinion.
Still looking for the note about level 15 Besieged.