The bug:

     Hoglin stable bastion remnants can generate with one or two of the side ramparts facing backwards into the stables due to having identical jigsaw blocks on either side of the side_wall_0 and side_wall_1 structures, which means that either one matches up with either of the wall_base structure's jigsaw blocks - I fixed this by simply changing the names of the jigsaw blocks to minecraft:side_wall_0 and minecraft:side_wall_1 in both the side walls and the wall base in a datapack so it specified which side of the ramparts it was on, which meant it couldn't face the wrong way. 
     The first attached image shows the problem with the front of each of the ramparts highlighted with a green line to show how they generated facing the wrong way. The second attached image compares an incorrectly generated hoglin stable next to a correct one in a datapack I made to restore the bastions so you can more easily see the problem.
     I noticed both the housing units and the treasure bastions only had one side rampart (which i don't know if it's intentional because the other structures have 2) which would solve this problem however it's just as easy as changing the wording in the jigsaw blocks to fix this.

How to replicate:

Either find a hoglin stable bastion or use a structure block to load in bastion/hoglin_stable/air_base, and then generate the jigsaw block that loads in the wall sections with jigsaws set to on (so you can see the problem) and layers set to 7 (so it loads in all the walls). If this doesn't work the first time try a few more times because sometimes it can generate the right way (although I generated it 5 times in a row the wrong way when I was trying to get one the correct way for a screenshot).