special update for you builders out there who depended on some of FAWE's masks in the past! Many of the old masks which were never reimplemented have recently been brought back. The full list of reimplemented masks, as well as descriptions, usage examples, and other details can be found in the PR's description here https://github.com/IntellectualSites/FastAsyncWorldEdit/pull/600 .
Light-oriented masks and the radius mask have not been reimplemented for various reasons, but are not totally off the table. Feel free to report issues with mask behavior or create a feature request on our issue tracker (https://github.com/IntellectualSites/FastAsyncWorldEdit/issues). Have fun!