But Keyboard Maestro will by far work most reliably/predictably when implemented.
Perhaps you could share what you have done with Keyboard Maestro and why it failed?
Basically the macros to open an app on KM are very straightforward. As fro placing a Window in a particular location, KM uses an x,y coordinate system which considers all of your monitors as one - so it’s just a matter of a bit of trial an error to get the coordinates just right.
There may be more elegant ways to do this in Keyboard Maestro, and you’d have to adjust for your purposes, but this is a basic start on what you want. It opens Mail on the left half of my main monitor, Safari on the right half of my main monitor, and BBEdit in full screen on my second monitor.
You can do all kinds of edits to the SCREENVISIBLE function calls in each one to get the placement just right for you.
Not particularly elegant, but relatively easy to do. Keyboard maestro to launch programs (or Bunch), Moom for placement and window sizes. Moom’s custom window placement is conceptually(for me) easier to do than keyboard maestro) can be triggered by a keyboard shortcut, which keyboard maestro can supply.
@tonycraine those were almost the exact edits I had, yet for my first app in the external (Things) the window of the app was almost completely off the right hand part of the external screen, and the second app (Fit R) appeared only in full screen, taking up the complete external screen.
Here are the edits I have, and am tweaking as I write this…