  The H to tau tau decays form the prime channel for the measurement of the
Higgs boson state and tests of the CP invariance of Higgs boson couplings. A
previous study has shown the viability of deep learning techniques for the
measurement. In this paper, the study is expanded. Effects due to the partial
modelling of experimental effects are discussed. Furthermore, systematics due
to ? decay modelling for complex cascade decays to tau^pm to a_1^pm nu_tau to
rho^0 pi^pm nu_tau to 3pi^\pm nu_tau are also addressed. Various
parameterisations are considered using low-energy collision data.
