@Takiro Oh, like writing the real-time but showing the numbers going fast due to the speed-up of the video recording? That's a good idea and possible since the speed-up is linear in my videos. I'll have a look to if it is something possible to do in Kdenlive, but I'm afraid it will not be simple.
I'll try to launch a bottle in the Fediverse: ping #kdenlive experts, around. Do you know if this ↑ is possible?