If I proxy bitcoind 127.0.0.1 on debian it automatically uses stream isolation for its connections to peers. I know that if I proxy bitcoind in workstation via 127.0.0.1 it will automatically forward to gateway (because it says so here: Dev/anon-ws-disable-stacked-tor - Whonix), but will it still use stream isolation?
There are various quality degrees of stream isolation.
It’s not mixed with Tor Browser traffic since that uses a different SocksPort at least.
A dedicated port would be better.
Applications using (a) socks user name(s) appropriately have best stream isolation. In that case, it shouldn’t even matter if a shared (not a dedicated) SocksPort is being used, and that being reliable. These are upstream features of Tor or the application, unspecific to Whonix.