That "nest of objects point to each other" makes no sense ... RAII is just a technique where you choose to tie resource management to the lifetime of an object (i.e. acquire in constructor, release in destructor).

If an exception gets thrown, causing your RAII object scope to be exited, then no problem - the object destructor gets called and the resource gets released (this is the entire point of RAII - to make resource allocation and deallocation automatic and bullet-proof).

If you are creating spaghetti-like cross-referencing data structures, then that is either poor design or something you are doing deliberately because you need it. In either case, it has nothing to do with RAII, and RAII will work as normal and release resources when the managing object is destroyed (e.g. by going out of scope).

RAII could obviously be used to allocate/free a resource (e.g. temp buffer) from a free list, but is not really relevant to arena allocation unless you are talking about managing the allocation/release of the entire arena. The whole point of an arena allocator is the exact opposite of RAII - you are deliberately disconnecting individual item allocation from release so that you can instead do a more efficient bulk (entire arena) release.