I'd get the drawings to be sure (unless you want to open it up yourself to confirm) but I wouldn't call the framing in my interior walls "Studs".
Honestly, I'm surprised the interior wall supported the bunks at all. When I opened it up, its basically 1x4s, except at the corner, where its TWO 1x4s stapled together.
Something to consider, depending on what you are attaching there and how much stress you think you'll induce.
Also of note, the bottom of that interior wall was NOT screwed through the sill plate to the floor. There was a 1x1 piece under the lower bunk. Wall was stapled to that, and THAT was screwed to the floor. I'd say look good and hard at how it's constructed.
Lets see if I have a pic of that wall "framing"....