Ciao, I’ll share my thoughts:
level 1 is expected to be easier than level 2 in which difficulty spikes sharply.
I played it with a system of mine with 4 characters roughly equivalent to lvl1 for a generic osr and they managed to explore all the complex in 2 sessions, the group was badly mangled and one of them died but they were very clever and cautious, and avoided most of the dangerous enemies (but also most of the treasures).
I would say maybe lvl1-4 is good, but much is dependant on the number of creatures roller on the random encounters.
Also the amount of treasure is around 1k gp, which for a deluxe version I considered boosting it to around 1.5k
Hope I helped!