Do I need faster SD cards for high bit-rate video or log recording on a Fujifilm X-T4?

Both of those are video concerns, and have no real impact on still photography at all. A faster card may allow you to shoot more pictures more quickly, or to shoot longer in high-FPS burst mode (depending on the camera's processor), and that may matter depending on the kind of photography you do. If you don't spend a lot of time shooting in machine-gun mode, it won't be a concern.

As to the "what are those" questions, high bit rate is any high-resolution, high-speed, high-colour, low-compression video mode. That requires a lot of data to record compared to lower-resolution video, lower frame rates, or video with lower colour subsampling (say 4:2:2 - and if you don't know what that means and don't care, don't worry). "Log" is logarithmic sampling - a way of recording a very "flat", low-contrast video that contains a whole lot of information, but requires contrast and colour grading to make a reasonably good-looking final video. Think of it as the video version of a raw image. (That's not quite true, but it's a decent analogy. Like a raw image, a log-format video is just the starting point, leaving you with some work ahead before you have something that looks like a video clip.)