How to have the same Animation on different mobile devices

My problem is, that we have a 2d game where different enemys are coming from the left or the right side of the screen and follow different paths due different animations. But on devices with different aspect ratios the enemy would either "spawn" in the visible area or the player has to wait a longer time til the enemy appears.

I thought i could set first x-position keyframe depending on the device, but i can't - i.e. very odd! And i can't set up a new animation within a script, because they are too complex. That's why path-following isn't an option too, or are they?

Any other options or hints?

Kind regards, Thomas

ps: we talkt about 240 animations, so having different animations for different devices can't be realized., if only because with android and ios we have more than 7 different aspect ratios.