I see. That’s generally why the engine is time based and not frame based, to avoid such problems. The only problem that produces is one where if it’s really important to you that you see ONLY the keyframes the animators made in the 3D package, you have to get rid of interpolation, and then you sacrifice timing slightly anyway.
If that’s what you’re after, I would suggest checking into the approach of using stepped curves in your animations. Make your Maya (or equivalent) clips using stepped animations, and in the clip’s page on UE4, switch from Linear to Stepped. That will make it so animations frames “snap” from one to the next, meaning the same animation will always show up - and since the system is time based it will drop frames when framerate severely drops, but will never show you more than the X number of keyframes you originally made, since the animation isn’t interpolating anymore.
It’s important to remember that this way, your animations will never exceed the original framerate from a visual standpoint. Meaning, if you used a 30FPS timeline in Maya, your animation will “update” 30 times a second, not matter how many frames you actually render in the game. That’s why it’s recommended to use a timeline in your 3D animation software that’s similar to your target framerate for the end product.