Hello again Katrin.
In regards to your “visions”, I am afraid that all I can think of is that we know so little of the mind… so, because we want to learn, we should do our best to not create obstacles to the process.
Yesterday Geshe Namdak quoted Sarawa, more or less like this: “We are already confused, why should we be more confused?”.
So my only thought is, unless these experiences are particularly disturbing your meditation, maybe you should do just as you said above: just watch them come and go.
This is just my very ignorant opinion… always keep that bucket of salt at hand!
All the best to you,
and to all,