1. You can install packages libndm and ndmq from archive (for mipsel - http://bin.entware.net/mipselsf-k3.4/keenetic/archive/). But it's deprecated.
2. You can install package jq and use RCI interface. Something like
wget -qO - http://127.0.0.1:79/rci/show/interface/Bridge0 | jq -r '.address'