does the software walk you through making them happy?
The software doesn't have to be happy. The client has to be happy. The Audiobook Mastering system sometimes creates intentional distortion in the middle of the process. But only I, you and the studio audience knows that the distortion will be cleaned up later. So in that one case, you can't rely on the software responses.
I don't know that any of the tools are massively different than they were earlier in your career. The last, I think two versions of Audacity are 64-bit applications instead of 32-bit to accommodate Apple's insistence that everybody do clean changeovers for their machines. Bottom line is you can't easily run your older and newer Audacity versions on the same machine (that I know of).
I can be corrected there.
Do Not, (I think it's obvious) make any sort of change in the middle of a book, project or show. There was a recent post from someone who was forced to change locations in the middle of a book and was horrified when the sound in the new place didn't match the old. I think we convinced them the majority of the difference was simple volume shifts and after accounting for that, the two presentations came very close to each other.
I don't remember, are you reading for audiobooks? The standards for those haven't changed in a while so even though your process may be a little different, it should in the end come out OK.
Did you use any plugins or separate apps or processes? That may be the place to worry about compatibility problems. DePopper, DeClicker, DeEsser?
Step through a typical presentation as a test and do a screen grab (Shift+Command+3) of each tool setting panel. Shift+Command+4 allows you draw a box around a part of the screen and capture that. That's how I made this picture.

- Screen Shot 2019-05-15 at 15.21.51.png (40.52 KiB) Viewed 235 times
That's one of the steps in the mastering process. Much more important was a odd setting for DeEssing that I got to work really well, and then forgot to write down. Gotta love those screen grabs.
I know it's possible to have several different Audacity versions and that seems to be what would do you the most good. But I don't remember the spells, or even if it can be done in your circumstances.
I can ask.
Koz