First I'd suggest to test the DSN from linux, assumung you are using unixODBC ODBC driver manager:

isql -v HL7Interface2 myusername mypassword

What do you mean by "I concatenated them into one file, all.gz."?
How did you do that?

You may have already fond this in this community, maybe not: 

Caché ObjectScript Quick Reference  (aka "the Cheat Sheet")

You can use/reference %SYS.Journal.Record class and method from Python to work with journal files, what's your problem with that?

What do you need to achieve?

I don't think that implementing %SYS.Journal.Record functionality in Python from scratch would be easy and I miss a good reason why anyone would want to do that.

To work with journal files IRIS provide an API implemented in %SYS.Journal.Record class and that's what we are supposed to use.

If the target of your transformation is an HL7 message you should not unescape HL7 content, if you do it your HL7 message will be invalid.

In your example \T\ is the escape of the "&" character that is a field separator.

If the target of your transformation is not an HL7 message then you do need to unescape your fields.

Instead of using $translate or $replace I suggest using the Unescape() method in the EnsLib.HL7.Segment class, this assure you are unescaping all possible escaped character.
The Unescape() method is in the segment class, so first you need to reference a segment (any segment), then the Unescape() method. I'd use the MSH segment, so your method call will be:
source.GetSegmentAt("MSH").Unescape()

Then all you need is to pass the field reference, for exaple:

source.GetSegmentAt("MSH").Unescape(source.{AIS:UniversalServiceIdentifier.Identifier})
or/and:
source.GetSegmentAt("MSH").Unescape(source.{AIS:UniversalServiceIdentifier.Text})

Documentation for your product/version is here:
https://docs.intersystems.com/latest/csp/docbook/DocBook.UI.Page.cls

Note that Caché 2018.1 supports .NET up to 4.5, it seems you are using 4.8, I'm not sure it works with 4.8.

In Caché Management Portal, go to System Administration -> Security -> Users, in the _SYSTEM user row click the "Profile" link (last column), after the .NET error, what's the content of "Last Reason for Failing to Login"?

Almost impossible to help without details on the .NET code you are using to connect and call Caché.

I think examples use very old version of Visual Studio

You are using an old version/product too, Caché 2018.1.

I think the product IS fully released since more than a week now:

InterSystems announces General Availability of InterSystems IRIS 2024.1

Or I'm missing something?

You even posted in the announce!

found no documentation on how to set a VECTOR Datetype on pure object level

Maybe you can have a look to the documentation of $vector, $vectorop, $vectordefined and $isvector intrinsic functions.

Congratulation Robert! 🏆🎖

Definitely deserved recognition.

The prerequisites for the InterSystems HL7 Interface Specialist certification include the training course and "At least 6 months - 1 year designing, building, and performing basic troubleshooting of HL7 interfaces with InterSystems products version 2019.1 or higher."

Actual/real experience will definitely help in passing the certification, theoretical study and some exercise may not be enough to gain the knowledge required.

In the exam description page you can find a list of "Exam Topics and Content". All questions in the exam belong to those topics.

Last but not least, everything is contained in the documentation.

Where/when do you want to know it?

Usually you get this information looking at the trace of the session/message.

Or you need to know the sender from within your BO code/method?

Parameter runtime computation works fine, you can test it from terminal:

w ##class(ECUH.BPL.ClassMethods.X509CredentialAlias).#VALUELIST

Long story short, you cannot use runtime computed VALUELIST in this context.

I suggest using the proper, officially documented way to implement your requirement, see my first answer above.

Using the Curly Braces a parameter is evaluated at compile time:

Parameter VALUELIST = {..GetValueList()};

You need to evaluate it at run time, in that case use COSEXPRESSION:

Parameter VALUELIST As COSEXPRESSION = "..GetValueList()";

The the relevant documentation is:

Defining and Referring to Class Parameters

I just realized that with IRIS for Health (and I maybe also HelthShare connect) ZAUTHENTICATE is mapped to HSLIB and you should use/modify HS.Local.ZAUTHENTICATE class in HSCUSTOM namespace.

If you are using HealthShare, and I do believe so, please read the following documentation (login required):

Custom Authentication Processing using the Local ZAUTHENTICATE

There you will find:

Important:

The ZAUTHENTICATE provided with HealthShare includes callbacks that allow you to add custom processing at specific entry points. Do not modify the supplied ZAUTHENTICATE. Instead, add your callback processing as class methods in the class HS.Local.ZAUTHENTICATE

If it was mapped to HSLIB, then I think you are using HealthShare, if so, you are not supposed to change that mapping, instead you should use/modify HS.Local.ZAUTHENTICATE class in HSCUSTOM namespace.

I believe the mapping will be recreated when updating/upgrading the system.