To clarify, there is not a Control Switch in your definitions on the screenshots.
Control Switches are for doing specific things and also don't have a Tap and Hold.
Also, I was not thinking about the fact that a stand-in switch doesn't change when changing layouts/views.
Looking at the screenshots you have above, you are moving between 2 layouts (3&4). I was thinking the FX and More FX were 2 Views in the same layout. Are they actually 2 layouts? I don't use the factory ones myself.
That's correct. My CS Switch is not defined in my SS's. If you'll hang on a few minutes, I'll try to describe to you how the so-called CS switch is setup. (It's actually the 2nd of 3 greyed out switch areas located in layout 7, connected as described with respect to the front panel Stand-in Switches > FM9 SW3 > Layout 7 : CS Switch > 11 Layouts > Inc/Dec.
When you look closely at the 3 greyed out switches (essentially #'s 10, 11, & 12) you can see faint lettering indicating two of the switches purposes. The 2nd switch reads its custom name FX / MORE > MLM. Although I don't know if this config will answer the OP's question, based of how well the switch will work or not (it isn't possible for me to test this, I'm short by one switch! LOL).
(Plz forgive the dust and glare!)
The above image describes how the OP's stand-in switch would need to be configured regards the front panel (there may be alternatives I'm not yet familiar with).
Regards FX and MORE FX as being 2 views, they are not. They're separate layouts you can regularly view in the factory and OFM9G configs. As yes, the idea is to inc the OP's layout count from 3 to 4 with a wrap to return to 3 on a subsequent tap. The HOLD is designed to transfer to layout 9 (Masterlayout).
The only reason the switch is named a CS Switch is because of a Mr. Obvious reason. Layout 7 is named CS Switch. The front panel mimics that and reads back both Layout 7 and its title, CS Switch. I did see that that next category over is CS MIDI, but I'm not using MIDI with my rig currently.
If CS is related to that somehow, feel free to elaborate. Perhaps describing layout 7 as CS Switches does not serve any good purpose. The FM9 has only 6 CS Switches. This gives me pause to rethink how to utilize layout 7. As toggles, inc/dec, channels perhaps, but it's really a catch-all for seldom used if ever used stuff. It might be possible to set up the my previous CS2 and CS3 within any of the remaining layouts and tweak the Stand-In Switches to reflect that.
You've provided me with something to think about overnight. My feeling is that if it will encourage conversation but prevent confrontation, all for it. (Danged if I know what layout 7 is really named, my former factory and OFM9G configs are not followed religiously.). I'd really like it if it were something practical and useful. I'll check back in with you tomorrow and try to understand my reasoning regards the first 6 effects across the bottom of layout 7. My gut feeling tells me they have something to do with CS 1 > CS 6, but why is an entirely separate story.