The X axis is a long-standing headache for Junior owners. Fortunately I never had too much trouble with mine, but I did have to re-level it a couple of times. The main problem is not so much the fact that the X-axis isn't perfect (hardly any X-axis ever is), but that the Junior doesn't have any sane way to level the bed to compensate for a wonky X-axis.
Anyway, I'm not sure what the official designation for the size of Torx driver the X-axis uses, but I had a bit that fit it in my set of computer/security screw bits. Whatever its official size is, it's very close to the size of a 2.5mm hex driver, but unfortunately is not compatible (I've accidentally, or in a pinch, been able to use the Torx driver to drive 2.5mm hex heads, but I certainly don't recommend it -- you'll eventually round off your screw, or your driver, or both).
The weird thing is you say that the right side is too high -- the way the X-axis is constructed, over time the right side tends to be too low because things slip and the axis sags.
Short of finding yourself the correct bit to actually turn those screws, two ideas come to mind.
First, you could somehow raise the right side of your bed. This is easy enough to do by loosening the bed clamp screws and slipping a few scraps of paper under the clips to raise it up a bit. However, this presumes you can loosen those screws, which are actually the same size Torx screws used on the X-axis
I probably shouldn't even suggest this one, so DO THIS AT YOUR OWN RISK! But if you're desperate, you could try a modified version of the XYZ-offical leveling technique and place something thick, sturdy, and nice and square (I never liked the idea of using the power brick...) on your bed and jogging the Z-axis down until it touches. If your axis is too high on the right, then the left side will hit first. Don't keep jogging it down too much, because the left side is not the target here and you could wind up breaking your bed glass or knocking something else out of alignment.
But with the X axis resting on the object at the left, firmly but gently press down on the right side of your X-axis. If you're lucky you might feel just a little give, and it will droop down a little, hopefully just enough to give you a slightly better alignment. Don't overdo the force here, for all the same reasons as above -- you don't want to break anything or make anything else worse.
Even if that works, I still suggest finding the right driver for the screws, and if your alignment is better, at least tighten them down again.
Side note: I always thought the XYZ-recommended method for doing this overlooked the glaring fact that even if you do manage to get the X-axis aligned on top of your power brick (or some other object), the tendency will be for the stresses of the mechanical parts and fasteners to droop back down as soon as you remove that object, because you're removing supports that placed balancing forces on the machine that kept it in alignment. Even if it's a miniscule difference, you'll never get a fully level axis doing that. It would be far better to use a square object as a measuring tool, rather than as a supporting force, to align the axis, but that of course is much harder for a consumer company to try and communicate to a layman.