I posted about this a few times over the years and got no response from anybody. You are probably going to be on your own trying to figure it out.
Here is what I discovered when I moved back here 3 years ago. The database was full of bad or obsolete information for AEP in NW TX (AEP Texas) and SW OK (Public Service Company of Oklahoma). Many of the site number and LCNs listed in the database were wrong. Either incorrect information was submitted to begin with or AEP made major system changes several years ago. I got all the information corrected for most of the sites withing about 100 miles or so of Wichita Falls that I can hear on a regular basis. I can't really help with particular information for S TX.
This system
American Electric Power / West Texas Utilities Trunking System, Various, Texas - Scanner Frequencies and this system
American Electric Power (AEP) Trunking System, Various, Oklahoma - Scanner Frequencies both appear to really be the same system.
I think probably
American Electric Power / Central Power and Light Trunking System, Various, Texas - Scanner Frequencies and
American Electric Power (AR/LA/TX) Trunking System, Various, Multi-State - Scanner Frequencies and proably the AEP systems in other states are all part of a large multi state trunked system, but I can't receive anything outside the local area there is no way I can verify it.
Were you ever able to follow complete converstions or trunk track it properly? If you don't have the correct frequency/LCN order you can't properly receive an EDACS system.
It is hard to tell what is going on by looking at FCC license data because some AEP sites have up to 80 frequencies licensed when in real life only 3 to 5 are used. At some sites the LCNs follow frequency order on the license and others they don't.
If they added or changed LCNs at your local sites you will need to run Unitrunker on the system with one receiver and scan all the channels in convetional mode on another scanner to be able to figure out which frequency is which LCN.
Since EDACS is no longer supported it would not surprise me if they replaced it with OpenSky or something else.