Yes, it is a little gamebreaky. But fun. While no one can 'hide' dreams or filter them from being broadcast on the Hitomi, Road can still use her powers to give Light dreams that would supersede what he might have otherwise dreamed that night. However, as we understand it, she would have to be there physically every time in order to do that. It could be a fun plot and I'm sure the gods would perhaps influence him a bit to have some terribly personal dream during one of the times she wasn't there.

We would expect backfiring, too. Like he might find himself having horrible nightmares from Road even if it hides what he wants to be hidden. Or perhaps Road herself would be in them - like a merged dream on the network. (You'd probably have some PCs getting their panties in a bunch then, too.)

Or perhaps backfiring on Road. These are just some ideas. The bottom line is it's a fun plot and her powers won't be nerfed exactly, not after the powers uncapping, but given the whole premise of Kannagara we would not want this to be an ongoing thing of him being able to hide dreams or her able to "filter" dreams long-term for anyone. Road herself would likely face some retribution for long-term repeated tinkering in such affairs.