Speaking for CS5.5, you can run all main apps and get your work done. There are some tweaks, e.g. for a better view of Adobe Illustrator CS5.1 font menu. You don't need to install legacy Java runtime. Creating empty Java runtime folders is all it needs.
Sometimes CS apps are crashing on starting up or quitting and occasionally there are macOS crashes with kernel panics and restarts on a MBP 2019 with T1 chip. What didn't work for me was Adobe Acrobat Pro XI, so I do use Adobe Acrobat Pro 2020 and before the update I ran version 2017 (all TLP perpetual license).
The major problem is macOS Mohave itself. As you need to run it with an unsupported HFS+ filesystem, to get a productive Adobe Creative Suite 5 or 6, updating macOS is a hassle, as it just works on APFS. However, there are no more macOS Mohave updates and so that's more or less a problem of the past.
Concluding, if you can run CS5 or 6 on macOS Sierra 10.12.x, I'd recommend doing so. If you must run it on macOS Mohave, it works, but you should test, if it really works for you.