Like I said, people can like the explanation given, or not. But not liking it doesn’t mean there is no explanation.
I’m not sure what you’re referring to as far as people writing the lines in ROTS, and what they meant, etc. I’m just going by what was actually stated in the movies, and the associated events. I don’t know how a subjective assessment that the writer of ROTS was creatively lacking affects what was said and what occurred in the movies themselves. I also don’t know how the amount of time McDiarmid was aware of his recurring relates to whether his reintroduction was explained within the movie itself.
As for an army of Snoke clones, judging by what we see on-screen, the cloning operation on Exogul pales in comparison to what was going on on Kamino in the prequels. I didn’t see thousands of Snoke clones, I think there were about 3 in the tubes?
And even if they made a bunch somehow, AOTC specifically describes how the Kaminoans modified the genetic code of the clone army to be more docile and to grow faster. I would imagine that an army of Snokes would also need to be made more docile and more prone to taking orders than the original. Would the comparatively small operation on Exogul be able to do that? And if so, would modifying genetic code also mess with the force abilities/midi-chlorians of the clones? (Yep, the dreaded midi-chlorians. Canon, sadly. I hate it too, but as it exists, and we’re talking about genetic manipulation, it’s unfortunately relevant.) Maybe it would. And based on the “botched Snoke clones” we see, it seems like the crew on Exogul haven’t quite worked out all the kinks yet.
As for whether cloning of force users specifically would work, we have to look at midi-chlorians again. They’re present inside the cells of all living things, so they’d be present in the clones. Would they have the same levels as the original? If the cells were the same, I imagine they would, yes.
Now, I think it’s VERY likely that a lot of people here will turn and run at the mention of the dreaded M-word

, but despite not being mentioned in the ST, they’re still a thing and can’t really be undone (except for maybe with Special Editions of the prequels? We can hope.)