Bed leveling between towers Mini Kossel

I am currently using repetier firmware for my kossel. I have gotten my bed level at X, Y, Z, and Center by adjusting the end stop offsets and modifying the delta radius. Now my problem is that in between the towers is not. So travelling between the Z tower and the Y tower (directly opposite X Tower) the nozzel really drags the paper in between the two, and then on between X and Z towers it is actually not dragging at all. Almost every guide I've seen only mentions calibrating these 4 points to level the bed, but after doing so I'm still getting these other errors, so my question is, what do you have to adjust to get the bed level between the towers?

Also, I have a seperate question reguarding steps per mm and diagonal rod. In getting the X, Y dimenions accurate I was initially going off a guide that told me to change the steps per mm to adjust the size using (current steps * expected size) / (actual size) = new steps per mm. Then I've read other guides that say you should be adjusting the diagonal_rod_length in order to get an accuracy in the X, Y dimensions. So I was wondering, what the difference was between those, and if there is a time to use one over the other? Thanks

It looks like either position of tower X needs to be moved counter clockwise a bit or position of tower Y needs to be moved nearer to the centre. Hard to tell your description is too vague.
But the good thing is I do not need to guide you since you can read what to do in this document: [github.com]
Read the comments in it. If you are good at math you can even try to execute it.

That guide (which recommends (current steps * expected size) / (actual size) = new steps per mm) is misleading. It works like htat in cartesian printers. In delta, that works only approximately and only for Z coordinate.

The other guide (which recommends adjusting the diagonal_rod_length in order to get an XY accuracy) is misleading too. That advice may work in some special cases (e.g. when only diagonal rod is wrong and when you print the object at specific location with a specific orientation) but in general it is wrong.

In a linear delta machine, X, Y, and Z errors are all tied together. If your steps per mm are correct, bed is flat, towers are equidistant to each other, and the bed is perpendicular (or almost perpendicular) to the towers then if you perfectly level the bed then also your X/Y dimensions will be perfect (or almost perfect).