I was asking my followers about what theory I should do next when @Dannex suggested Ba-Ado-Mishram
Which in my usuall style got me to go over everything we know for certain about BAM.
And while I didn't get a theory on powers, I think I know where she is.
In order to get to where Mishram is currently located we must first learn about the people who captured her, a quick read of the Gemstone Archive reveals two things related to BAM.
1. BAM had connected to the "Parsh" drawer 30-20 fourth emerald
And something I think to be overlooked yet of more note
2.BAM's forces were going somewhere drawer 19-2 third Topaz
Rall Elorim, is the only thing that this Radiant can think of after what appears to be multiple attempts to take Feverstone, I think it safe to assume this is the case.
Now Rall Elorim is an intresting place, but at the same time very vauge, it has yet to be shown, in fact we only know a few things about it
1. It's called the city of Shadows for a reason, and Brandon won't tell us
2. It has an Oathgate
3. and it was one of the First places Odium took on Roshar.
Now the only reason I could think of for a city to be called the City of Shadows was an unmade and currently only three are unaccounted for
Chemorish
Dai-Gonalthis
and Ba-Ado-Mishram
One of the first two was at the Davar household
and one was so devestating that they caused the scouring of Aimia, but nothing like that has happened to either place, and was maybe in Shinovar.
Another thing is the term Shadows, Shadows are created by a mixing of light and darkness, Light that is dark, or Voidlight, which happens to be something BAM could create.
And nothing but shadows has been made known to us, almost as if the unmade were limited, or bound in some way.
On top of that Odium's quick arival to Rall Elorim I believe is because he knows BAM is there, but has so far been unable to free her. Why? becasue his forces have only looked in the Physical realm.
Knowing that Unmade have a large pressence in the CR
The recreance Radiants knew this and did something clever, just like when a human is physically brought into the cognitive their CA is replaced so they brought the gem into the CR to hide BAM's cognitive presence.
Aluminum gives an additional layer of protection and then place it in a convienent nearby city with access to the CR so as to hide any other oddities from the cognitive side, have the sibling keep the Oathgates from allowing CR travel, from any place but the Horneater peaks which is almost acrossed the enite continent, and you have yourself an airtight prision for an unmade.
In addition
WoK prime spoilers
TLDR
BAM is in the cognitive realm around Rall Elorim