Use it for a while to “break it in” then rebuild the center. For some reason this seems to work for people having a stubborn build. Also with zero tension on any tension bolt you should be really close. If you are not you should have a look at your printer and check for accurate dimensions and axis perpendicularity, most printers print at an angle on one or more axis because most people will never notice. There is not even a way to adjust it out until the newest marlin firmware that can do it digitally. For most these are the first dimensionally critical parts they have made.
As for which bolt does what. Start with all tension bolts loose and tension one set and check to see how it moved. It should only take one or two sets, if you are tensioning them all you are fighting the opposite tension bolt.
It also looks like you might have used something other than PLA? PETG and ABS tends to be too flexible to tension much it just stretches. and if you mixed materials they have different shrink rates and could also be causing issues.
Some of us run a small zip tie through the middle of the stepper connectors to tie them together. I used a piece of half inch heat shrink to keep them together.
