The LST follows a specific pattern, and the failures, emergencies and non-normals will be pretty easy to guess in advance. i.e. you will be doing a SE go-around at DH etc.
The fact of the matter is that a TR is hard if it is your first jet TR, and the time spent in the FFS is so short and there is so much to cover that people find themselves in the LST after 4-6 sessions and easily get overloaded. It may also be likely that the xmas period had breaks and/or multiple instructors which does not aid the learning process.
The KLM instructors are most likely to be very experienced, and if they are not confident in your ability, then they will fail you. After all, peoples lives would be put at risk if you are released to continue your training.
I would be most surprised if further training is not allowed/accepted.