I have successfully compiled DoomRL (and by extension FPCValkyrie) on windows That one's easy. Another person has successfully compiled on OpenPandora of all things, a third has made progress on a linux build that requires backporting some FPC bug fixes, and to the best of my knowledge no one has gotten it working on a mac. There's a couple known bugs that are on hold til KK gets a newer mac too.
Between the open sourcing and the kickstarter things are still chaotic. Most of these convos are being had straight on GitHub now and it'll be a while before things shake out and we determine who maintains what. If you want to be the apple maintainer you are welcome to it :). But there's nobody that I know of who can help you right now.