If for some reason you want to change the Type name in Descr_Strat, you also have to go to Data\Descr_Character.txt and put the same name in the "strat_model" line for that unit.

For example, when I changed many of the Strap Map captains in ATW I used a different model for each of them. Because of that I had to create a separate entry in Descr_Strat for each one as well, with them all having a unique Type name. Then I had to go back to Descr_Character.txt and make each "strat_model" line point back to each new entry I had made.