I'd like to see planetary interiors in future versions of Space Engine. Click on a button showing a dissected planet and the planet opens up to reveal its internal structure (atmosphere, crust, mantle, and core).

Also, comets would have animated jets coming out of them to tell them apart from asteroids.

Hope all these was not off track from the current development schemes too far

Since there is already a set in the commands lis in which velocities or accelerations can be customised via a script, so a guided tour is possible in current SE. But can you add commands that emulate the function of actual W,A,S,D, etc. for movements and rotations, including a limitation of lasting time linked to frame rate and not system time (like in current star motion blur).

It would be extremely hard to make a proper flying path using such script. Instead of that, I will add flying path recording feature with editing options. You just enable recording, fly wherever you want, stop recording, and then optionally edit resulting path as a spline. After that, save it into file, and you can use it to render video in the offline mode (with settings set to max etc).

Calculations suggest that it will take billions of years to reach synchronization or even more than the estimated life of the sun. The Sun's rotation on itself, that of the Earth around the sun, and the moon around the earth would then be identical.