The setback areas in Bavaria are somewhat special because an experimental clause has been included in the BayBO. First, it must be checked whether the municipality has generally enacted regulations deviating from the BayBO, as Nürnberg has done, for example, and second, whether the development plan itself includes regulations regarding setbacks. If neither is the case, the narrow side privilege can be applied to a semi-detached house on a wall <16m in length. Now, your "site plan" is not very meaningful, since neither setback areas nor public traffic areas are shown, and the boundary setbacks are also incompletely specified. However, there is a suspicion that the narrow side privilege is already needed for a eaves side, so that the gable side must be calculated with 1.0H. The apparently existing slope must be taken into account here. The height from the (average) natural ground to the intersection of the outer wall with the roof surface applies, so not at 6.35m, but considerably higher near the 1m line. It seems the 8.90m were still calculated generously.