Abilities.txt is merely informational, like the readme.txt
The most common error in datafiles is the double blank-line effect, which acts much like an end-of-file. Useful when testing, though.
I wrote a quick little
Components repair tool which helps to fix erroneous newlines, particularily in multi-megabyte tech gridded mods.
SE4 will tell you if you have not enough tech or ability entries to match the number you gave. Having too many means the last ones will be ignored.
Typically quite rare, from what I've seen. Only a couple of times during a mod's development.