to All Things Plants. Not sure where you are but it looks like a rust fungus, presumably Coleosporium plumeriae:
http://www.padil.gov.au/maf-bo...
Some suggestions for treatment from Florida are here, scroll down to frangipani/plumeria rust:
https://edis.ifas.ufl.edu/pp17...
Perhaps someone in a climate where plumeria grows has experience of dealing with this disease but typically with rusts you need to try and keep the foliage dry as much as possible, and aim for good air circulation. I don't know if fungicides are an option for you or what might be available where you are.
