Here's another idea .... slacken all the brackets and legs half way , then screw the bracket at the bad end half woy in , you will be left with half the gap each end, you might still need to do a sall bit digging at the bottom right side ,then retighten everything back up, it will look even when...
Hi , the mozaic tile doesnt help to straigten out a wall,it should have been fixed 1st ......Try taking bath back out and dig the wall 1/2 of the depth of gap then silicone accordingly ...dont use trims.