You cannot capture packets using tcpdump if their destination is rewritten to a different port on a local interface.
It seems so, but I can't confirm it without installing and testing the service.
Check the output of
nslookup openwrt.org 127.0.0.1:8053; nslookup openwrt.org 192.168.2.1:8053; nslookup openwrt.org 192.168.10.1:8053
BTW (if you haven't seen it yet), It turns out that other users have similar problems even if they follow the guide strictly.
https://forum.openwrt.org/t/shadowsocks-client-on-router/141822