The actual GTY is containers.intersystems.com/intersystems/webgateway:2022.1.0.209.0

And there is no :latest defined
 

You may use input redirection as you find it in almost all Dockerfile installations:
 

RUN iris start IRIS \
    && iris session IRIS < iris.script \
    && iris stop IRIS quietly 

and iris.script (as example)

zn "%SYS"
Do ##class(Security.Users).UnExpireUserPasswords("*")
zn "USER"
 

I miss this in your Trigger code:
%ok: A variable used only in trigger code.
If trigger code succeeds, it sets %ok=1.
If trigger code fails, it sets %ok=0.  

see  %ok, %msg, and %oper System Variables

Class Reference of %SYSTEM.Status says:
classMethode IsError(statuscode As %Status) as %Boolean

Returns 1 if the statuscode contains errors. Otherwise, it returns 0.

 So if you get  [res] as  (0,....)  it is an ERROR!  
and therefore the result ofIsError should be 1.  It is an Error.

%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

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

from:
https://docs.jsonata.org/date-time#:~:text=JSON%20does%20not%20have%20a,%3A45%3A00.000Z%22%20%7D

for ISO 8301 
#1)  your source has to be a %TimeStamp aka. ODBC format
#2) it requires a LogicalToXSD() transformation.

>
write ##class(%Library.TimeStamp).LogicalToXSD($ZDT($Now(),3,,4))
2022-08-27T22:54:48.8953Z
But there is no defined Standard.

if it is a straight 8bit DB  you have the challenge to find out
how characters beyond the primitive 7bit ASCII are stored  e.g. ÀöÜß € ¡¿ è & é ç
is it ISO Latin 1 , 2 ,3 4, 5 ... or any of the horrible Win encondings

2 mistakes: 
#1^$get(node) delivers the content of variable node
but you would expect the result of $get(@node)  usingnode as global reference

#2) the better way is to use the implicit GET
Set node = $Query(^FromExtraMed(""),1,value)
write value  

for DOCKER:
docker exec -it [-u root] <container-name or -id>  bash
details

check this: 
https://docs.intersystems.com/latest/csp/docbook/DocBook.UI.Page.cls?KEY=EHTTP_inbound#EHTTP_creating_bus_service_config
especially this: 
https://docs.intersystems.com/latest/csp/docbook/DocBook.UI.Page.cls?KE…

The URL is then http://your-server-ip:your-port/