However in the five books of Nachman we do not find a specific connection between Rosh HaShanah and his grave site. He never took two two witnesses saying to come to his grave on Rosh HaShanah like he did for the Tikun Haklali.
(note 1) 16,32, 41,42, 59, 77, 90, 105, 137, 150 (Russians have a different way of numbering the psalms because they consider nine and ten to be the same psalm. So to them the numbers are different.)
If Reb Nachman had said anything that would have indicated that he wanted people to come to his grave site on Rosh HaShanah do you think that Reb Nathan would have omitted it? We know Nachman from Breslov wanted people to come to his grave to say the Ten Psalms because he took two reliable witnesses [neither of whom was Reb Natan] and declared this in front of them. And said specially that he would do everything to help that person. But he never took two witnesses about Rosh Hashana nor even said a simple statement like, "Come to my grave on Rosh Hashanah."
When he wanted people to come to his grave he said so openly. When he wanted people to come to him, while he was alive, on Rosh Hashanah, he also said so openly. But he never said or implied to come to his grave on Rosh Hashanah. And in fact no one, including Reb Nathan, came to his grave on Rosh Hashanah. They came to Uman, but not to his grave.
When he wanted to discuss his grave he did so in many ways. But his grave was never mentioned in the context of Rosh Hashanah.