In regards to Tibarn, there is still the question of his JP voice actor Tatsuhisa Suzuki (who also voices Alfonse, Berkut and Ranulf).
I am aware that Suzuki's whole affair and hospitalization have been over for a while now and that he returned from his hiatus, but IS has still seemingly avoided using any of his characters (which again includes Alfonse, FEH's main lord) since February 2021 (when Alfonse got his Day of Devotion alt).
It'll be interesting to see if IS decides to keep him on in those roles or if they recast those roles. At any rate, it's something IS has to make a choice on eventually given the characters who are involved.