Is the money spent on banquets after the opening of exhibitions and the efforts put into their establishment halal or haram, taking into account the limited government support for the association?

If the expenses for organizing exhibitions (such as food, transportation, and other costs) are part of the association's activities, and they are disbursed with the permission of the authorized person, then there is no objection to organizing them using the association's funds. This is not considered an infringement or a betrayal.