Getting paid “In-kind” is only actually getting paid if what they offer in trade equals the value of the service you provide.
If the appointment is 2 hours and your rate is $40 per hour, but they offer you two tickets to the event worth $20 each:
A) what good is a ticket to you for an event you will be interpreting?;
B) that works out to half your going rate, minus $20 for a ticket you don’t need… so $10 per hour?
That’s not trade. That’s augmented volunteering. They can do better and you’re worth it.