Thank's Gustav.
Yes the red/yellow plumes were probably perculiarities to the musicians rather than the officers and soldiers as the Otto Manuscript shows a carrot shaped plume of green, with the officer having the yellow tip. Two years on and into Spain I reckon they may have been re-uniformed and decided to stick with the more standard appearance all be it maintaining the yellow cuff flaps.
Anyway after 200 plus years, there is a lot of guess work and I await an 18mm figure with the fancy shako chords
Cheers
JJ