I realise it would be miles better to be able to cut on multiple selected objects with one cut and I am unhappy that it does not. I should have clarified why it only works on each object seperately in the report, so I will do here.
Mainly, it is a limitation of the way the knife tool is already designed. Without going into too much technical details (unless that is preferred?), to have a semi working version of the knife tool in multi-object edit mode completed within a week I had to implement it this way. I believe the way the knife tool currently works would have to be massively changed to allow cutting of all objects with each cut (a similar problem is this) and I am not familar with the areas of blender’s codebase that would make this work.
I am sorry I could not deliver a better version where all objects could be cut simultaneously. I hope at least I was able to lay a foundation for someone with more experience and more time than me to come in and rework the necessary things to make the knife tool work in such a way.