It was a first draft, I can't stress that enough to people.
Capcom could have asked Romero to change things to be a little more faithful to the game, but instead they fired him because they didn't like his screenplay treatment.
Romero, according to interviews back in the day, did indeed write multiple drafts. There was never confirmation on what changes were made, though an unconfirmed sourced cited Chris Redfield being changed back to a S.T.A.R.S. member and (probably) monsters being cut for budget.
This seemed to be a trend, as the McElroy draft (which was the first writer) had almost every monster from the game (including the mutant bees), and each draft tended to shed material until finally Anderson's draft included only three monster types and a minimal amount of sets.
Romero's drafts were the most faithful to the game in tone, while the other writers varied. McElroy wrote something that may have been okay from what I gathered, but the others tended to go either for generic low-budget zombie film or something in the vein of the Doom movie.
The reason Romero was fired was because Constantin Films couldn't decide what they wanted to do. The quote from Capcom of "Romero's script wasn't good" was probably relayed from Constantin when Capcom asked why he was fired. They probably never saw the actual screenplay. In Romero's words, "They wanted a war movie."
I've broke down Romero's script before on other boards, detailing why he made certain changes based on his storytelling style, but it essentially came down to Romero wanting a film with social commentary and a diverse cast of characters.
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