What's the error message you're getting from this? The only time I couldn't enter a city it was because I did a bunch of modding and when I tried to enter the city the game kept allocating memory until I had to kill it. I did a ton of adventuring earlier this year on 44.02-44.06, probably 200-300 hours, and I never saw any city corruption.
I've been playing adventure mode for two years. Whether I'm playing Vanilla or Masterwork, ASCII or tiles, friendly squads from my hometown will attack my companions in every world I generate. If there are travelling NPCs then they will either
a) Generate infinite clones of all monsters in the region after dying
b) Crash the game upon leaving travel mode
The only way to yield and cease hostilities is to teleport your companions away. This also prevents with drowning and suffocation.
Maybe the entity id gets corrupted when an adventure mode site (the area loaded when you exit travel mode) overlaps with a town/city/camp/ruin, and the client tries places the NPC in both the town/city/camp/ruin and the overworld site so that it is in two sites at once. Since a single travel mode tile can simultaneously exist outside of a town/city/camp/ruin while overlapping onto it so that a travelling NPC entering or leaving a town/city/camp/ruin has two data entries for a single location. Or something. I have waited two years for this to be fixed, but Adventure Mode is still unplayable and there are no handlers or workarounds to fix corrupted saves.
The icing on the cake is that since Dwarf Fortress consistently crashes every 16 hours due computing smoke, having a key pressed while loading a site, or moving too quickly (Adventure Mode often moves you two tiles when you move once, so there is no way to prevent this) this forces you to save often in order to mitigate crashes. Yet saving often increases the risk of file corruption, which causes crashes.
It is impossible to roleplay in Adventure Mode, as resting in towns or cities will regularly corrupt your NPC files, whereas sleeping outside of towns and cities guarantees a half-hour fight with bogeymen that indefinitely chase you by teleporting next to you and massacring entire towns when you try to flee.
Want to play as a mythical beast? Get ready for loyalty cascades, crashing on site creation, and exiting at player forts. Want to generate a custom map? Get ready for drowning, freezing and cave-ins at spawn, along with corrupt entity IDs and respawn loops. Player Forts corrupt saves in adventure mode.