I’d argue SSG and caching are the same solution just a difference in where the cache resides (disk vs memory) and warming strategy (on-demand vs preemptive)
How often does a bug tracker get that much traffic? And using an SSG for one when tons of the queries will have specific filtering terms doesn't seem so great either.
For fellow website admins, this is your regular reminder to use static site generators, where possible, and server-side cache where not.