Manuals printed way ahead of time might not have options that are added later in roms.

The only manual addendum I know about is the one for the ZR1 diagnostics here:

https://www.ipdb.org/files/570/Bally_1994_Corvette_Manual_Amendment_16_9890.pdf

It covers the A2.17 change, but I don't see anything about A2.18.

When Williams was making these manuals there was constant pressure to make changes all the way up to and in the middle of production, despite the fact that the printer of these manuals needed the documents in final form many weeks in advance.

There are MANY, MANY, MANY errors and omissions in pinball manuals, it's just something that the technicians had to get used to. And pretty much it was only technicians who looked at these books anyway.

For a lot of years the documentation on video games and pinballs was so bad that I would say 'Real techs don't need manuals'.

It was easier to figure out everything for yourself instead of relying on poorly checked documentation that referred to a machine that was produced before many changes were made.

This is definitely not something you should obsess over. It was the 90's. Mistakes were made.