The most useful indicator seems to be rapid leg movement combined with no change in position. That's not typical cat criteria. Rapid legs usually mean position

The most useful indicator seems to be rapid leg movement combined with no change in position. That's not typical cat criteria. Rapid legs usually mean position change (running). I would use a very small accelerometer on a front paw connected to BLE enabled microcontroller on a collar. That's the easy part. Triangulating position is harder. GPS would be too heavy, but you could use BLE signal strength from 3 different receivers around the house. I imagine someone has solved that problem before. Or, you could put Yuri in a closed area with camera monitoring. Train a YOLO5 model in Yuri vision and let it monitor the area. You would have to simulate a seizure though. You could make a fabric facsimile of the animal and place it in different areas on its side. The shape of an animal in a seizure is not the same as when it's sleeping. It would be up to you to determine the difference.