There’s a known issue with Civilization 5 on Linux, where it randomly crashes with a segfault. On Reddit the issue is discussed and the proposed solution is to limit the number of simultaneous threads to 8 or below.
On my system I found that this was already the case and further lowering it to 4 reduced the number of crashes (but they never went fully away) while the game seems to still run smoothly.
I run Steam as Flatpak and the coanfig file is here located in ~/.local/share/Aspyr/Sid Meier's Civilization 5 or ~/.var/app/com.valvesoftware.Steam/.local/share/Aspyr/Sid Meier's Civilization 5:
[User Settings]
MaxSimultaneousThreads = 4
Happy playing!