The advice in this video may help...
[video link]
(Also, since the video was made, it's also possible to use a small amount of bloom & glare to smooth jagged edges).
So, the final advice in this video is to use highlight clamping to reduce "the jaggies." My question is: Is it not preferable to do highlight clamping in post processing (e.g., Photoshop) or is there a disadvantage to doing it this way (i.e., does Corona have more information available to it during the render that it can somehow use to produce a better clamped scene)?
Because, if there is no disadvantage to highlight clamping in post-proc, that seems like the best solution since you defer the choice of whether to do it or not to a later time and you can do so in a lossless and selective manner in post-processing. If you highlight clamp during the render itself, the clamped highlight information is irrecoverably lost.