From memory this is actually a part of the af design and there isn't a adjustment as such.
Many of the compact cameras from that era had a af mark in the middle that was a little like [ ] ]
You had to use the extra right hand mark when used at one end of the zoom to get accurate autofocus - sorry I can't remember all the details as it's been nearly 10 years since I sold them..
I can accept that 1 of the cameras you have is not focussing correctly, but both have the same problem? I suspect it is actually part of the camera design as described above..
As for adjustment - yes you can align/re-align the af sensor on a camera - but in the old days this was done by plugging the camera into a computer, and adjusting the AF alignment based on a set of standard paramaters...
At Canon we also used to have a IRED sensor unit to check that the IR sensor was aligned correctly - you pointed the camera at a mark on the box, and the LEDS would light to tell you if the AF was aligned correctly.
You can also check he alignment using a digital camera with a IRED filter on it - IF the camera has a reasonably strong IRED system then a digital camera can pick up the af beam, and you can check the alignment by pointing the camera at a target, and using the digital to see if the AF beam and the mark are in alignment...
One other thing I've just remembered - some of the cameras from this era had multi beam focus - where they sent out 3 AF beams and used fuzzy logic to decide which one to use to focus on. You could also set the camera to single beam focus by putting the camera into a particular mode - time to download a instruction book..
Sorry for being so vague.hope this helps....