Cunningly-disguised shakuhachi player (see Dressing modestly).

At the New Grove dictionary of music and musicians we used to debate some weighty issues of principle (see e.g. here, for Tibet; and here, for China).

Lower down the scale in our discussions was which typeface to use for “ethnic” instruments. The theory was that roman should be used for instruments that had passed into common English usage, whereas less widely-known terms should be in italic. So some, like sitar, shakuhachi, and shamisen, were deemed worthy of roman; whereas most others, like sarangi, zurna, and qin, were still considered exotic enough to be given italics. Some genres or ensembles, such as gamelan, have been awarded roman too—maybe even gagaku.

Of course, it’s all rather subjective, and subject to changing perceptions. I believe some instruments graduated from italic in 1980 (and the 1984 New Grove dictionary of musical instruments) to roman in the 2001 edition.

For instruments like the shakuhachi, “well-known” is a lofty conceit, of course—last I heard, the shakuhachi isn’t constantly on the lips of Albanian villagers or East End pub-goers.

Piffling as the debate may seem, it serves as a marker of our degree of ignorance, with roman as a badge denoting admission to our elite club, depending on which genres happen to have gained a certain exposure in the West through the vagaries of exploration, research, recording, touring, and hype.

Taking the long view, many instruments of WAM (solidly roman) have a history of acculturation from foreign origins, taking time to establish themselves (cf. China). See also under What is serious music?!