The project is licensed under the MPL 2.0 (and 1.0) which states:
Each Contributor hereby grants You a world-wide, royalty-free, non-exclusive license ... to use, reproduce, make available, modify, display, perform, distribute, and otherwise exploit its Contributions, either on an unmodified basis, with Modifications, or as part of a Larger Work;
So the answer (at least for Saxon) is yes! Just make sure you conform to the licence requirements and you're good to go.
Each Contributor hereby grants You a world-wide, royalty-free, non-exclusive license ... to use, reproduce, make available, modify, display, perform, distribute, and otherwise exploit its Contributions, either on an unmodified basis, with Modifications, or as part of a Larger Work;
So the answer (at least for Saxon) is yes! Just make sure you conform to the licence requirements and you're good to go.