sGra’i-tsher-ma (“Grammar Thorn”) is considered by some to be a name of Smṛtijñānakīrti. Cf. Smith 2001: 315, n. 599; The Blue Annals, vol. 2, p. 252. See also Tshe-tan-zhabs-drung, Thon mi’i zhal lung (p. 36). But why was he called so? A nickname given by Tibetans? Or could it be a Tibetan translation of a name in Sanskrit?
But interestingly, the expression sgra’i tsher ma occurs also in Rong-zom-pa’s Dam tshig mdo rgyas (p. 294), where it, however, has nothing to do with sgra in the sense of “grammar” but in the sense of “noise,” and hence it is clearly understood there in the sense of “noises that are thorns [to the ears],” that is, so to speak, “sound/noise pollution.”