Ahhh, now I see 

There are two roller switches!

That's a new puzzle for me too   

I explained very much of the process in my WIp from pahe 112 to 115
https://www.viperpits.org/smf/index.php?topic=537.msg177914#msg177914

Well, do remember one thing, if your lights work with BMS without DCSbios, then these lights should work on their own with DCStoF4 without DCSbios with DCS

The same was true for my simshaker issue:

- Simshaker has 2 versions depending if you use DCS or BMS
I was using the DCS version that required a declaration in the DCS scrip file which as I said above, does not work
But basically, The simshaker BMS version works with DCS as well through DCStoF4 and that one does not required the script.
So you basically can avoid the declaration in the script file and have the simshaker work through BMS shared mem, like the rest of things

The trick is to have as few as possible declarations in that scrip file of BMS to avoid potential conflicts, pass everything through BMS sharedmem with DCStoF4 and it works much better.

So basically, setup everything (Arduino driving LED's, Simshaker, etc) for BMS Shared mem, then use DCStoF4 to convert it all back to DCS. Rather than having specific software (simshaker, DCS-BIOS, etc) for DCS, and specific for BMS, to avoid DCS' flaky declarations? Makes sense, things should be much simpler with DCStoF4.

Can you use arduinos other than a mega with F4TS? I understand you couldn't run several OLED's (DED/PFL/FFI) using an uno because of memory constraints, but for simple LED could I get away with Uno's? The documentation seems to say only Mega's can be used (be nice if I could use wired ESP32's as well, but thats another thing entirely) 

In the new release of BMS, that roller switch is supported. It indicates that the canopy is closed.
The switch you mention is not used in BMS. However, you can use it as the roller switch 

If you have the roller switch and use it as the "canopy closed" signal, you could use the other switch for actually open/close a canopy if you have a canopy installed on your pit. In that case, the switch actuates the motor to open/close the canopy (frame).

I still don't get it, if in the real plane you use the toggle switch to lower or raise the canopy, why would we want in our cockpits the roller switch to do that job?

The "roller switch" is atually used in BMS. It is the detection that the canopy is closed.
The other switch that you can manually toggle, and is pushed back when the spider is "closed" is only needed if you want to implement a "real" moving canopy 

That that you said really confused me. I'm still running my cockpit with BMS 4.34 and I use the "other switch that you can manually toggle". Is momentary down, so if you release the canopy stops and doesn't keep on closing, as safety measure, and locks in the up (opening canopy) position. It works as such in BMS, I don't understand what you said about  " is only needed if you want to implement a "real" moving canopy"