Reading up on what both of these trace flags are for, they do not seem to be related so enabling them both has their own advantages, specifically with AX. I do not see why you would not enable 2371 if needed, regardless if 4136 is or not.

4136 - deals with the parameter sniffing process.

2371 - deals with auto update stats and when the query optimizer will attempt to update stats which just basically throws out the default 20% change rate.