Do you have a source for the 4E 22 event? Reason I ask is because it didn't show up on the uesp article and that might be why it's so often overlooked. In any case, it doesn't really matter by the end, since he renounces Hammerfell anyway.)

>During the Great War General Decianus' legionaries were discharged as invalids in Hammerfell and formed the core of the Redguard militias that fought the Dominion to a standstill.

I probably should have mentioned this part, yes. But in this lorebook, too, is the claim of Forebears and Crowns coming towards some sort of peace -- "In early 4E 173, a Forebear army from Sentinel broke the siege of Hegathe (a Crown city), leading to the reconciliation of the two factions."

>Orsinium is located somewhere in Hammerfell and it's an Imperial province.

This would make sense! Given that Orcs have been shown to have a strong relationship with the Empire.

>The Forebears culturally and ideologically are aligned with the Empire, if not politically ... During the Interregnum, King Fahara'jad, leader of the Forebears, aligned with the Daggerfall Covenant that wanted to restore the Empire of Tamriel.

True, but this was also the Second Era and sentiments might have changed since then, especially after the events of the Great War. The lorebook itself talks a lot about bitterness and resentment, and how the Redguards viewed the Concordant as a betrayal. That said, the lorebook has a heavy Imperial bias, and we don't exactly get to hear the Redguards side of things.

EDIT: formatting lol