A bit of advice: a group should never sign a contract without knowing how they are going to get their equipment to the venue, and whether they can afford to get it there. Also, they are cutting things a wee bit close. Given that this is an unfamiliar instrument which is likely at least 100 years, old, there may be any number of issues to sort out.

Not meaning to be critical here. I've been in several groups that featured rare and unusual instruments, and have had things break, get lost, malfunction, or fail to appear. I understand why some performers who only travel with instruments and equipment that can be easily replaced;-)