The reason you're confused is that this room involves a strange property of the Regenerators that is not at all intuitive. I had to look over the critical moment of my demo a couple of times before I could make sense of what was even happening.
I'm putting that property behind a spoiler tag just in case, even though I'm having trouble imagining someone being upset about seeing it accidentally, because it really isn't very clear.
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×If a Regenerator O is on a force arrow, it will not copy itself against the direction of the force arrow. So, for example, a Regenerator on an east-facing force arrow will not make a copy on the tile to its west.
As for how that relates to what you're supposed to do:
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×You are correct that you're supposed to end up with three ROs - that's the first step. The arrows are then used to reduce their numbers further.
