Thanks again. On our local Jobeserver, C & Java assignment evaluations are working pretty well. I am now struggling to setup SWI-Prolog. Already installed SWI-Prolog compiler on Jobeserver and tried /var/www/html/jobe/application/libraries/swipl_task.php as given, however SWI-Prolog is not appearing in the Coderunner Question type.
The set of question types is defined by the set of available question prototypes. Adding explicit support for a new language to the Jobe server doesn't give you any new question types.
See the CodeRunner documentation on User defined question types and Supporting or implementing new languages. You'll see in the second of those links that you don't actually need to add explicit support for a new language to Jobe; you just have to install the language on the Jobe server. You can then access it via a script in one of the existing languages. This is the preferred approach because it doesn't create maintenance issues when Jobe is updated.
Virtually all languages at University of Canterbury are nowadays run via Python scripts, because it gives you much more flexibility.
While going thru the second link, I found: "Turn on the Twig All checkbox, so that all fields of the question will get processed by Twig, once the template parameters have been set up." Where can I find this checkbox?
It's in the topmost panel of the question authoring form, as shown in the figure below. However, it's a new feature and may not be in your version of CodeRunner. It's only relevant when you're randomising questions, so if this is still about adding prolog to CodeRunner you can ignore it.