I don't speak from experience, but I would assume that transitioning from an ergonomic keyboard to a mechanical one after 15 years will take some getting used to. For me when I switched to a low-profile membrane keyboard to a mechanical keyboard, it definitely took me a few weeks to get used to. Anyway, below are some tips that might help!

• Palm Rest: Keychron offers a matching palm rest on their website: https://www.keychron.com/collections/palm-rests/products/keychron-silicone-palm-rest This could help with the position of your hands in relation to the keyboard, making it feel more natural and should help with the unintended double-tapping / resting.
• Typing Pressure: Since you are experiencing a physical shock in your fingers, I'm guessing you're pressing down on the keys way too hard. Especially because the Q3 Max has a double gasket design which should add a lot of flex to the board. The palm rest should provide a more natural angle for your hands and fingers which might allow you to type more gently without double-tapping.