I want to know if it legal to use bane bots transmission in a robot?
Nothing in the rules says that you can’t.
Just to quote the rules,
<R32> COTS items that are generally available may be used on the ROBOT. The parts shall be generally available from suppliers such that any other FIRST team, if it so desires, may also obtain them at the same price. A specific device fabricated by a team from non-KOP materials for use by that team does not have to be available to others; however, the materials from which it is made must be available to other teams.
NEW BaneBots transmissions are most likely legal. Old ones that are out of production, or with a design different than the current model, are probably not legal.
Yes they are Legal as they satisfy the COTS items and sefety rules. Be careful if you have old ones lying around as the designs have changed quite a bit over the years and the older ones may no longer be available. (this would make them no longer COTS).
I think there are quite a few uses for BB products in the FRC game this year.