%BI classes date back to Miner (DeepSee-1) and just were left in Caché over a decade at least
while its functionality was replaced by %DeepSee classes more than 10 years ago.

Of course, you can map all %BI.*  classes to some DB where you have R/W access and import it from Caché.
that's about 300 Classes.
BUT:  no one can tell you if they compile correctly
AND: you have to take care of the hidden %bi*.obj (~430) and other deployed code which you can't compile, but import and pray they work.

SO: this doesn't look like a  promising approach.

Therefore I'd suggest migrating from %BI to %DeepSee in Caché first and to IRIS next

The questions seem to imply the view from a management position:
 However, how would you recommend to people aged between 20 and 30 to start, maintain, or reboot their joy, excitement, love, or interest for coding and software development?

As I had the responsibility for a team of specialists my experience is such:

  • Is there any other motivation as simple payment? If yes, the person could be raised.
  • Any small success is a motivator. Especially if recognized by management.
  • Curiosity is another motivator. Exploring something no one did before could be driving. My personal trigger always was. "This not possible"  It is known as the "Galilei effect": And she (earth) is moving anyhow!
  • Competition within a team works but is risky if competitors are too different. The weaker one may give up if it sees o chance.
  • The best of all motivators is fun. Often in a team of 2 rather equal qualified people.

HTH

SOAP is quite specific and critical to data format and structure.
You might extend it, but then Edge Server is the active part and you depend on its regular "broadcast".
If Doc Server should be the active partner I'd rather suggest to use JDBC in Linux.
Your actual $get might be embedded as a Method projected as SQL Procedure that you call.
There exist examples to even execute COS commands by that approach:
see: ObjectScript over ODBC

Hi @Ditmar Tybussek 
Raw containers from ISC are always just US versions. (aka. international)
If you use Dockfile you have all freedom to condition  YOUR container according to your needs.

MgmtPortal: this is a good old  CSP feature that looks for the primary language of your browser
and translates your pages to DE if available.
Docker itself seems to have no idea about your environment.

Your keywords >90% COS + SAMPLES indicate your background.
if you don't intend to win a prize in a contest adapting some CSP Samples will be fastest. Forget any ZEN.
And just call the CSP class. never the .CSP itself.
what I mean:
NOT http://localhost:56773/csp/samples/form.csp
BUT http://localhost:56773/csp/samples/csp.form.CLS

It's my quick and dirty approach