Never tried to bend tamarind, but if it were me I would use steam rather than dry heat to get the bend, as its a bit more forgiving. I would also use a form with a reflex, and side support for the lateral bend. Leave it clamped at least a day.
It can be really tricky with some of the less used but excellent bow woods(eg Guava), as there isn't as much info on how they behave with heat bending. If you have a decent sized scrap of tamarind you could do a practice run and see how it behaves.
