I found it ! Not an easy one...
And I do not consider it as a bug of ES.
It's not the cheat mode itself.
But the way "instant blueprint" works when creating an object :
i.e. it revives the ghost of an object that was never created before.
And apparently, it does not trigger the "on-creation" event again, that I use to follow all entities creation.
So this mod is not good : most mods (like mine) are waiting for classical behaviour, not cheated turnarounds...
Anyway, I added a little test to avoid the error (please update on portal), but beware that any object created this way cannot be detected by any mod.
And now Qon, please, be serious, STOP CHEATING !!! It is giving me heart-attacks finding those impossible bugs...
PS : have a look at my new mod, very useful for mega factories : viewtopic.php?f=92&t=30163