Like...in universe fiction?
Yep. Here's what I've got fo far. I'm trying to essentially make a "history" of the show which is showed through PHO interludes for BCF. (Source: LordRoustabout)
Avalon: Web of Magic as a replacement for the Nasuverse (which would not exist on Earth Bet due to the collapse of Japan). The rough idea was that the series Princess Gwenevere and the Jewel Riders was much bigger on Earth Bet, leading to its sequel series Avalon: Web of Magic becoming a long-running animated series rather than a series of young adult novels. The project was handed to Kinoko Nasu who basically turned it into Fate with the serial numbers filed off. The production team included a lot of Japanese animators who had immigrated to America. They were throwing everything they had at the project to try to make a name for themselves, leading to a high quality and massively popular series.
the suggested details fall in line with what had already been established in the story, and that they be reasonable for the work in question. The series would have run on cable on Saturday nights, so would have been less restricted than a lot of other children's shows. It would have been known for pushing the boundaries of Standards and Practices on occasions, but everything would still have needed to be fit for US broadcast.
The broad summary of the details of the show, as established so far in the story and WoG posts:
The series followed from Princess Gwenevere and the Jewel Riders with Kinoko Nasu making several massive retcons:
-All the magic jewels in the original series (including the Sun Stone, the Heart Stone, and the Moon Stone) trace their origin to Kischur Zelretch.
-Princess Gwenevere was revealed to be a True Ancestor (His way of backdooring in a version of Arcueid Brunestud)
-Tamara was actually a homunculus
-Fallon (Aisha's favorite character) was killed by an Irish Lancer and later became a counter-guradian before being summoned as a servant
The characters from Web of Magic (Emily Fletcher, Adriane Charday, and Kara Davies) were used as stand-ins for Fate characters Nasu had already planned out (Rin Tohsaka, Sakura Matou, Illyasviel von Einzbern).
Shirou Emiya's character still existed relatively intact in personality and abilities, but with the name changed to Shawn Emiya (Causing Nasu to die a little inside). You also had an Archer equivalent.
Artoria was included with largely the same abilities, origin, and characterization.
Gilgamesh was also present as an antagonist in the series.
The Grail war existed as a major plot in the series, though Masters were referred to as Summoners and Servants were called Heroic Spirits.
Servants still had skills and abilities with letter ranks.
At least one film for Web of Magic: Apocrypha was released.
Web of Magic: Extra existed as a gacha mobile game with different plots (conflicting) depending on the region it was released in.