I don't think you can, the FPS is just whatever fps the game is running with and will always vary to some extent. Unreal Engine is designed such that a wide range of framerates is supported and a game can run fine whether it runs at 30fps or 300fps.
The value is random because your frame rate varies each time you run it and the large difference at the end depends just on how close the second to last tick was to the end time of the timeline.the timeline runs for 1 second, you have roughly 10 fps. One time you could have a frame 0.91 seconds after the start of the…