I see you insist on a baby steps analysis. Very well.
1 Your 'small, primitive ships' will be seen exiting from the cloaking fields of other ships AKA the federation easily becomes aware of the romulan cloack.
2 The cloaked ships, at all times, stayed beyond the sensor range of the federation - in its own territory filled with patrols, sensor posts, etc
- which means:
-cloak tactics will not be making an appearance in this romulan war beyond a few lines from the romulan side;
-for your small, primitive ships to be able to fool the federation in thinking there are no mother ships, they need to have long range warp capability - at the very least. Meaning, the non-idiotic strategy for the romulans would be to just send these small, primitive ships - now not so primitive long range warp ships - from Romulus, skipping the cloaked mother ships step;
-the Federation not 'seeing', even once during the war, how, in its own space, small, primitive ships exit from the mother ships; or not deducing the existence of romulan cloaking technology that hides their ships until they're deep in federation space is both convoluted and makes the Federation people seem inept;
-the federation is now depicted, again, as highly incompetent in not even being able to stop small, primitive ships while they come from far beyond the star system/beyond federation space;
Anyway you try to twist it, your explanation remains highly convoluted; indeed, it has de facto become just a vehicle to use the word 'cloak' during the romulan war, sacrificing large chunks of story believability for this.
PS - This won't change no matter how annoyed you are by this fact, AverageWriter.