Generally when there is an issue with stroke detection, the source of the issue is your watch orientation being set incorrectly.
Follow these steps to check your settings:
1) Open the Apple Watch app on your phone
2) Tap General > Watch Orientation
3) Check to make sure these settings match the hand you wear your watch on.
Once set correctly, the stroke detection should drastically improve.
Our Community Champion would love to help! Contact us at email@example.com or use the messenger.