Some standardized definitions can avoid confusion and errors. I use these::
Front wall- wall in front of the seated listener.
Back wall- wall behind the seated listener
Speaker distance apart- distance between centerlines of the tweeters (this works even for speakers like Magnepan)
Use the center point of the tweeter at the baffle surface to define measurements from the front wall and side walls. Speakers come in different shapes and sizes and the drivers are not always in the same vertical plane, ie many speakers place the tweeters a bit farther from the listener. So use the tweeter position as the reference point. It does not make much sense however, to compare positions of different speaker models since their cabinets and designs such as ported, sealed, driver size, etc determine the best placement. But these measurements are useful for someone trying to decide on the best type of speaker for their particular room.
Toe-in can be defined as an angle but that requires some geometric type calculations. I have defined it for myself as rise over run or distance change from one front corner of the speaker to the other front corner. But I found the most accurate way to set toe in is to use a laser.
I use a laser measuring device to dial in the speaker toe in. Place the measuring tool on top of the speaker and square it and center it to the front baffle. I do this by using a block of wood. Align the block of wood to the side of the speaker and then place the laser measuring tool against the block of wood. ( I made the width of this block of wood to place the laser tool at the speaker tweeter centerline). I extend a tape measure across my listening position and then activate the laser. The laser spot shines on the back of my listening position and I can now position the toe-in precisely using the scale of the tape measure. Repeat for the other speaker.
Does this sound over the top? C’mon, most of us here embrace this level of intensity. How could I listen without anxiety otherwise?