MM team tenacity math

Short answer: yes, I think your math looks correct
See 12/4 Dev Post on this subject

• Unique abilities apply prior to leadership.
  
• Most abilities DO NOT stack multiplicatively with other abilities
  

This is a bit of a unique case since the Trooper does not exist at the start of battle. I would assume that the leadership ability is calculated first and then the trooper unique is added when he is summoned. Since the MM lead is only triggered "at the start of battle", it would not be updated or recalculated as characters are added or lost.