Add "language" as a native field to users, and allow language to be an option at project/task level. This could then be used as a pre existing filter in Project workload balancer or used in your AI assignment suggestions. the same could also be done for "skills and certifications"
For a truly global agency model that uses off shore and near shore creating these fields and pre filters or AI suggestions would allow all markets to manage offshore and near shore employees capacity better. as well as better manage multicultural/multi language global projects.