in the Questionnaire section right before question number 12 it states

Have you ever been involved in or had any of the following?
Check the appropriate answer and provide an explanation:

and then the questions


12. Have you been a Part 141 Flight Instructor?
If I am reading this correctly, even if I was not a part 141 instructor but the program that I received my ratings from was part 141; then I should mark yes and explain?

Seems pretty simple.....Have you been a part 141 instructor? Either you have or haven't.
The instructions are general because the questions are specific. If you mark yes and then explain that you once had part 141 instruction, The response will most likely be RTFQ! Not trying to be gruff but I would just answer the questions as written.
Have you been a part 141 instructor? yes/no
If it is yes then elaborate. If no, then no explanation required.