I hope this question even made sense cause I know nothing about all this programming language stuff.

.aslx, which is very similar to XML (this is for a game file).

OK, I think there is a difference here...
The programmers of Quest.exe use a mixture of Visual Basic.net, HTML, and some other internet coding...
(Actually, it could just be VB.net which uses HTML format...)
BUT, "you" the game programmer that uses Quest, use the Quest language which seems to be related to HTML formatting...

Everything listed so far is correct, plus CSS and Javascript.

...along with a variation of C for the actual scripts.

I highly recommend downloading notepad++ ( https://notepad-plus-plus.org ), as it's a great program/software for writing, reading, editing, and trouble-shooting code (but it's just a text editor software, so you can't run/test code, to do that you need to download a IDE/SDK software like 'MS Visual Studio', but this stuff is a bit more, and probably too, complex for non-coders, without help from us. So, just stay/stick with using only a text editor program/software, like notepad++, for now, and learn to script/code first).

Within (having downloaded, installed, and opened/started) notepad++ (up), select the 'XML' choice under the 'languages' drop down in the horizontal menu bar at the top, as it seems fully compatible with quest's similar 'tag' structure/style of coding)

quest's OBJECT coding structure uses a very similar structure/style as that of the web languages' (HTML, XML, etc) code structure of 'tags':

you can study/learn web languages via this site (which will help you with using quest's similar 'tag' coding too, seen in the code box below):

https://www.w3schools.com

the 3 main/basic/original web languages are:

1. HTML (Hyper-Text Markup Language) (used for creating the website/webpage)
2. CSS (Cascading Style Sheets) (used for formatting the website/webpage)
3. JS (JavaScript) (used for creating actions/events/etc for your website/webpage)

and use them to create your own website/webpage!

and here's quest's OBJECT structure, using a similar 'tag' coding:

// the 'tags' are the use of the '<' and '>' symbols/characters:

// (horizontal):

<XXX>XXX</XXX>

// or (specific for certain things only):

<XXX />

// or (vertical):

<XXX>
  XXX
</XXX>

<!--
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
-->

<asl version="550">

  <include ref="English.aslx" />
  <include ref="Core.aslx" />

  <game name="example_game">

    <attr name="start" type="script">

      <!--
        // SCRIPTING
      -->

    </attr>

  </game>

  <object name="room">

    <inherit name="editor_room" />

    <object name="player">

      <inherit name="editor_object" />
      <inherit name="editor_player" />

    </object>

  </object>

</asl>

quest's scripting coding uses a format/style that is similar to the 3 main full-bore programming languages:

1. C++
2. Java
3. Python

and if you want to learn these 3 main programming languages, I can help with it/them

you can study/learn their scripting via this site (you do have to register/make-an-account, but it's free): https://www.codecademy.com

here's an example of quest's scripting:

if (game.state = 0) {
  msg ("GAME STATE: 0")
} else if (game.state = 1) {
  msg ("GAME STATE: 1")
} else {
  msg ("GAME STATE: 2")
}

now, quest's internal/core/engine/software itself's coding... that uses a hodgepodge of programming languages/softwares:

1. FLEE
2. C#
3. VB.NET
4. some Assembly Language (probably)
5. etc?

There is a problem with non-latin characters in objects, owning probably to limitations in the languages used.
I'm trying to make Quest work in Greek, and an expression like

If (Got(πέτρα)) Then (Remove πέτρα), Else (Print "Δεν την κρατάς!")

throws an

Error running script: Error compiling expression 'Got(πέτρα)': SyntaxError: Unexpected character: πLine: 1, Column: 5

Any ideas anyone?

Put all the variables in English and only print the text in Greek.

Further to DL, call the object "stone" and give it the alias "πέτρα".

Yes, this is the answer I was looking for! Thank you! I will work on fine-tuning the Greek translation, now.

Cheers!