No those are like *hit* marks in japanese if you look at the hawk they are on the wings where they were pierced too. The significance is the fact that her hair either broke susanoo or beat the speed he could bring it out
Well those are SFX for piercing noise I think .... But knowing Kaguya's Byakugan skill, she probably hit a vital point at worst case scenario ... Whose significance we wld know later on.
That's actually a SFX(sound effect).Kaguya pierced his arm with her hair,nothing more.But if this continues she'll close all Sasuce's chakra points ,similar how Neji did to Hinata.
naruto and sasuke are utmost fodder if their seals are blocked,,,,
plus i doubt hagoromos seals are that weak to begin with that kaguya can lol block it and end the world GG