How can I make these drivers "Blend" these shapekeys properly and with acuracy? Is there a way to blend several shape keys with only drivers properly? This seems very possible but complicated to understand, like for example in how to use the equation, and understand it and how to setup the other values and properties...

The first two (1 and 2) shape keys seem to blend perfectly but the 3 and 4 doesn't do it well, the variable equation I used is from this answer: How do I get a driver variable to taper down to 0 once the variable is doubled?
This seems to work for what I need, which is for triggering a value a from 0.000 to 1.000 of the shape key slider (but being triggered from a different smaller/bigger value for the bone/object controller location, rotation or scale), and then from 1.000 goes back to 0.000 (also I need to know how I make that transition slower or faster, whether the speed of the activation and deactivation) but still I don't get to make the settings to blend all shapes keys when I move the empty...
I want the shape keys to blend at a specific value like for example if you notice in the cube, when it moves 1 key to 1.000, then when it decreases down to 0.500, and the 2 key increases perfectly hitting the same value at the same time, and then the 2 key goes to 1.000 and then 1 key goes to 0.000, and so on with the other ones....but I want to understand how i properly match up the values in every setting (from the equation and the generator modifier) to vary the speed of this, and without messing up the sums of values...

Also please can someone please explain very well about how to use properly the drivers f-curve editor? i have been struggling on how to use it to create this type of complex shape keys, and as well still no success looking for a really good tutorial for explaining all the possible equations to use, hacks,tricks, and the uses given for every type of tasks...
I need to implement this in a facial rig, so the cube is just a demonstration for what I am trying to do so I hope you understand the setup, (seems pretty easy setup but its actually not) for later use this in a facial rig (like when opening the mouth to smile but with different scale in each shape key, from closed smile to open smile)
Have you tried the &quot;Average Value&quot; Type, instead of the &quot;Scripted Expressions&quot;. For me, the &quot;Average Value&quot; and the correct adjustment of the curves always have resulted in what I expected it to do.