Just wanted to left some feedback as a novice coder, in case that helps :-) Hope this is the right place to do so, as I'm quite new to the site.
I see some people have pointed to issues related with the kata description, but in its current state, I found the information sufficient to complete the task.
I really liked the kata because it made me read carefully and plan step by step –the katas I have completed in the site so far are way shorter. Some of the steps needed where a bit more challenging than others, but I think the main challenge here is keeping things organized.
Good job!

I'm sorry, Ciprian Amza, I didn't see your changes while editing it myself. Maybe we should keep your more detailed explanation.

Changed description in following sentences:

(N.E. does not count either as failed student or as participant at all)

and

The best number grade from all the participants to 1 decimal place (check above)

After the apparently not so smart decision of approving a kata whose author has been inactive for some months, I tried to clarify the description regarding the open issues.

In this case I changed the first rule of error reporting to:

1. First check if the list is in the correct format (e.g. number grades corresponding to the pattern #.#), if not return this error: Error Message = "Invalid list"

I added these 2 extra notes:
Extra note 1: 'N.E.' should be treated as absence. It does not count in the average calculation of the grades, it does not count as participant. Extra note 2: 'F.N.B' should be considered 5.0 in the calculations (in the average field and in the best grade)

I also added this example in the description:
52018 F.N.B. should return: "Grade => 5.0, Average => 5.0, Failed => 1, Best => 5.0, Participants => 1"

This was added to the description. First check if the list is valid with all its variations. This means that the list respects the following format: 5 digits number + Grade ('F.N.B.', 'N.E.' or the format digit+point+digit). At this step only the format of the grade will be validated, not the value of it(for example: 5.4 is a valid format). If the format of the list is not correct

Done.

After all the issues raised here I am going to ask to move the kata back to beta.

the point 1 checks first if the list has the correct format, so 5 digits number and a grade, and only point 4 validates the grade

At no point does the description mention what is considered a valid grade "format". It only mentions what is considered a valid grade.

As I understand the description (and this part should be probably more detailed) the point 1 checks first if the list has the correct format, so 5 digits number and a grade, and only point 4 validates the grade. Most probably, in the initial list is checked only the format of the grade, not its value. Therefore 5.4 and 0.9 are invalid grades but have a correct list format (they pass point 1, but not point 4 of errors). If the grade would be 5.44, then the list format would fail as well.

What if the input is 52453 N.E.. What is the expected output?

These should go to the description.

But it is explicitly mentioned that a grade can only be one of (1.0-4.0, 5.0, N.E., F.N.B.). 5.4 or 0.9 isn't a grade according to this definition. So what is the initial list check actually checking?

N.E. : Didn’t attend N.E. counts as nothing. It didn't participate, it didn't fail, it didn't recieve any grade, but if that matrikel number appeared already or re-appears, there is an error.

F.N.B.: Failed free attempt (counts as 5.0 for grade average purposes) + ... in the following format:

"Grade => 5.0, Average => 4.46, Failed => 7, Best => 3.0, Participants => 13" So, the grade has to be returned in the digit+point+digit format. N.E. is nothing, is just to be ignored.

Lists always start with a matrikel number and then a grade, anything else is invalid. So, if the format is 12345 5.4, there is no invalid list error, therefore you have to go to the next point for searching an error.

But "50621 0.9" looks like a valid list because it respects the patern: 5 digit matrikel number followed by a grade. It doesn't respect the point 4 (make sure that all grades are valid). The fact that point 4 exists kind of demonstrates that checking if the list format is correct doesn't mean checking if the grade is correct.