In the published version of the paper:
the following error has occurred:
The formula in the third line of 3.5 on page 207 should have the commutator instead of the composition on the right hand side: $$ |[ P, Q ]|^\^(X_1,\dots,X_{p+q}) = \frac1{p!\,q!} \sum_{\sigma} \operatorname{sign}(\sigma) [P(X_{\sigma1},\dots,X_{\sigma p}), Q(X_{\sigma(p+1)},\dots,X_{\sigma(p+q)})] $$

The version on Peter Michor's homepage has not been corrected yet.