These section requirements for system safety are not included in 23 and 27.
Part 23 and 27 address those same requirements under their respective x.1309 sections. However, Part 23 was rewritten about 7 yeats ago and the current 23.1309 was moved to a different standard format.
If Lillium is claiming that they are as safe as an AB 350, (or a 609) they need to show they meet the requirements laid out in 1309 for Probability of catastrophic failure.
And they will from what I've seen written in the current and future power-lift certification guidance. That same guidance actually increases the use of failure probability limits across a larger number of certification requirements since the guidance is performance based. So its quite possible once certified the Lillium or other power-lift aircraft will be technically equal to or possibly exceed the AB 350 failure probability requirements.