User blog comment:Crimson and Darkness/Shin DxD 4 discussion/@comment-2208155-20200221084407/@comment-37560916-20200221142209

All the scenes that happen in England, are related to the Pendragon brothers, so it's not strange to think that Ishibumi developed Le Fay with Issei, specially because of the contract thing(Additionally, Le fay had another interactions with Ise in previous volumes, such as Dx5).

Remember that the Volume is not translated yet, and the spoilers are mainly from battles, we don't have information about the non-battle part(In which Ishi develops characters).

Also, remember that Incinerate Anthem ia a "special" Longinus that can choose another wielder,  I don't know if Alpecca Tyrant would do the same.

Again, We don't have all the background information to know exactly why Le Fay to battle against Meredith, but this is not bad anyway; Le Fay is powerful(Of course, nothing like Issei or Xenovia, but you catched the point) so is normal to have a battle between them(Also, Le fay had battle support, they were Arthur, Shirone and Kuroka).

Oh, and Le Fay was already in the Hyoudou Residence xD But I don't think this is a reason to lose faith to Ishibumi, actually, I feel the contrary,  I love how Ishibumi related these Shin Volumes, which I think are at a very high level from the other ones.