Sorry long question ahead.
Obviously you can only print one filament at a time and in H2D you only have 2 heads. With the filament switch, I thought you could have any AMS feed any side but I can’t get my head around that. Lets say I have a 4 color print, bottom of model 2 materials, 2 colors, top of model same material, 2 colors. I have 3HT connected via 4-1 to right, and 2 AMS to the left via another 4-1. If the 3HT contain 3 of the 4 filaments and one AMS has the 4th I don’t think this can print because one HT is feeding the left and another HT will have to feed the right at the same time. I don’t think this works, so the premise of any filament to any nozzle is not correct? I have to think where I balance the AMS and HT’s, yes?
The filament switch acts like the points on train tracks.
It allows each input to be directed to each nozzle (for dual nozzle printers).
You cannot feed one source while another source is in use.
Because you are using a dual nozzle printer, that potential exists.
As I understand it (I do not have it) the slicer recommends the best organisation for the spools between your attached AMS units.
In your example, you have three AMS HT units connected to one side, with three spools total and two AMS units connected to the other, one spool is in one of these AMS units.
Your print uses four colours total. Thus is not complicated and can be easily achieved without the filament switch.
The filament switch would only become used if the model colour needs necessitates using a colour from one nozzle on a different nozzle because it is easier.
If you follow the slicer recommendations and organise your AMS units accordingly, your print will print, but the filament switch may not be used.
The filament switch aims to assist when a complicated feeding process can benefit by swapping lanes.