Question

Hello and blessings.
In about a month, a famous non-Jewish singer is coming to Israel and will perform at a festival taking place in the north of the country. The singer’s performance has been scheduled for Friday at 9 p.m. (after the onset of the Sabbath).
I was asked to look into this for a relative (hereafter called Miri), who is an enthusiastic fan:
Assuming that no Sabbath desecration is carried out directly by Miri (buying tickets in advance, arranging accommodation on site after the performance), and assuming that Miri’s participation will not increase or decrease the amount of Sabbath desecration (since the festival and the performance will take place in any case) — are we left only with the prohibition of weekday-type activity? Is that considered Torah-level or rabbinic? Is the prohibition of benefiting from labor done on the Sabbath relevant here? Are there other prohibitions?
It is clear to me that in an ideal situation this question would not be asked, but since we are dealing with an enthusiastic fan who is not ordinarily meticulous down to the last detail, I am trying to find out whether there is room to be lenient and reduce the severity of the prohibition (after all, she did ask the question..)