I'd also add the Pseudojuloides wrasses to that list of sand sleepers if you can find a healthy specimen locally. And as far as the Halichoeres go, I wouldn't hesitate to add H. timorensis and H. marginatus, just start with juveniles. Some people have found the timor to be more aggressive, mine was fine with anything but tiny shrimp like sexy shrimp, brittle stars (he wanted to eat them, but they quickly learned to only come out at night which was fine), and small shrimp added after he was established and grew larger.Is probably go mostly sand sleeping species so Halichoeres, Anampses, Macropharyngodon, and Xenojulis.
As a starting list to look through I would say;
Macropharyngodon meleagris
Macropharyndodon bipartitus
Macropharyngodon meleagris
Halichoeres iridis
Halichoeres leucoxanthus
Halichoeres melanurus
Halichoeres cosmetus
Halichoeres lapillus
Halichoeres melasmapomus
Halichoeres trispilus
Anampses meleagris
Anampses neoguinaicus
Anampses melanurus
Xenojulis margaritaceus
Fairies and Flashers may not cope too well in an established tank with high activity tangs. I’m not too sure why but wrasses seem to be fine in high active wrasse tanks but not so much when there’s 2-3 tangs in there that are established. It may just be from competition of food.
But fairies to consider would be the larger species like;
Cirrhilabrus lineatus
Cirrhilabrus laboutei
Cirrhilabrus finifenmaa
Cirrhilabrus cyanogularis
They’re all fairly more boisterous species and will be able to hold their own with your current fairy (which appears to be a Cirrhilabrus chalasai).
To that list of fairies, I'd add:
Cirrhilabrus briangreenei
Cirrhilabrus filamentosus
Cirrhilabrus ryukyuensis
Cirrhilabrus isosceles (mine did well in a VERY busy active tank, but that's just my personal experience).
Cirrhilabrus bathyphilus
Cirrhilabrus lubbocki (which is smaller, but seems more than capable from holding its own in my experience)