@HemiRobo - You can ask all the questions you want and I will do my best to answer them.
A Pebble .pbw file may contain up to four different types of apps. If the root directory contains a manifest file then the app is compiled for an original Pebble or Pebble Steel running the 1x or 2.x firmware. If there is a manifest file in the "basalt" directory then that app is compiled for a Pebble Time or Pebble Time Steel. If there is a manifest file in the "chalk" directory then that app is compiled for the Pebble Time Round. If there is an app in the "aplite" directory then that app is compiled for the original Pebble or Pebble Steel running the 3.x firmware.
I know that some of the apps in the root directory that are compiled for the 2.9.1 firmware will run on the Pebble Time 3.x firmware but it is hit or miss in my testing. When you try to install a 2.x app on the 3.x firmware that is not compatible it can lock the Pebble and drop the connection from PWP. You can reset the Pebble and it will function correctly but without that app.
I stayed with the safe route and just go by what I know works for sure. I know the Official Pebble App is smarter than PWP and can determine if a 2.x app can run on a Pebble with the 3.x firmware. I need to figure out how to determine that but have not had the time so far. I know it is not a great answer but that is all I have.
Currently Pebble apps that have a worker component do not work with PWP. I hope to fix in the next PWP update..
Thanks for the heads-up about the spelling error.