Now I have tested the three versions, the original without mouse, the one with mouse, and the one with mouse and fixed LPT. Let´s name them 0, 1 and 2.
On the 0 version I can switch between 4 and 10MHz and the game remains the same, the movement of the pointer is perfect on both frequencies. The only noticeable change is the pitch of the samples.
Both versions 1 and 2 behaviour the same, perfect movement on all controllers at 4MHz, but if I switch to 10MHz, the pointer jumps outside the grid and freezes on all controllers. Only if I don't touch the mouse, I can return to 4MHz and play normal. If I move the mouse the Enterprise hangs. But it only needs a warm reset to return to Basic.
Sorry, I don't remember the emulator settings for a 10MHz machine.