I don't know why, this makes me a bit sad. You can sort of feel a game engine when you're playing a game. The GTA trilogy lost a lot when they did their remastering project with a different engine. Although I'm sure it can be done well. StarCraft remastered was done really well, but I believe they built on top of their existing engine.
As someone who played a few hours of the 1st Witcher Game... Good. No one seems to care about Witcher 1's engine, because it was hot garbage. Any engine (even an off-the-shelf one like Unreal5) will be grossly superior to the trash that the original game was. This remake can have slow, barely workable controls and pretty bad graphics and still be far better than the original game. They really just need the Witcher 1…
They picked an off-the-shelf engine that was designed to simulate tabletop games like Dungeons & Dragons in 3D. Maybe they got a good deal on it.
The bird's-eye click-to-move camera mode is what the engine was designed for, but the developers kludged in some keyboard controls because they were making an action game.
The odd timing-based fighting styles sort of make sense, because the engine wanted to handle combat with dice rolls on a mostly-fixed interval.
It could have turned out a lot worse, when you consider what they were working with. I hope they keep some of the weird quirks, like the rhythm swordplay.