As the user who came up with the stationary_restraints tag, I've seen it frequently applied to images that don't match the intent, and I think the terminology I came up with for the tag doesn't convey the intended idea clearly enough.
The goal of the tag was to easily find images containing pillories, shackles and other restrains that are affixed directly to the ground, a building, or at minimum, an object too sturdy or heavy for a restrained subject to move.
It seems like "stationary" is often being interpreted as pertaining to the subject, rather than the restraints themselves. Many of the mistaggings involve the subject having limited mobility, such as tightly bound by rope from head to toe, or having all four limbs restrained. (a pixiv tag readable as "4-limb restraint" was translated as "stationary restraint")
I'm thinking "mounted_restraint" might be a good alternative, but I wanted other opinions on how much clearer this describes the intended concept or suggestions for alternate wordings before actually making an alias request. (as it has far too many entries for a rename)