Clarification Bonustask

Does that entail only outputting points and mergecount per move from the complete move sourcefile and everything else is handled elsewhere without further implementation needed?
There is points.asm in the src. Is that relevant and should I collect them there?
Main seems to not have any logic for accumulating them.
But in the GUI the value actually changes on moves.

Assuming by outputting points you mean returning the sum of all the merges, yes, that is how the bonus task works. You do not need to implement the formula yourself or need to change anything in points.asm. Although you should probably make sure that merge returns these values as well and not just complete_move.

To be more precise what my assumption is:
merger returns points and mergecount directly, completemove gets stuff from merger, counts all merges per move and accumulates all points and then does the transformation and returns that as points.

You should not need to do any transformations in complete_move after merge returned. The task is only to make merge and complete_move both return the number of merges in $v0 and the summed up worth of the merges in $v1. Since each move only does one merge, I think you should not even have to accumulate points in complete_move.