Strictly replying to your question you can “review” (i.e. view) the iptables rules inserted by the load-balancing feature by using the following command:
iptables -t mangle -S
The chains introduced by this feature start with WANLOADBALANCE_.
However I also struggled with this feature myself and my solution was to use a custom script that “adapts” these rules after the load-balancing feature generates them. I’ve described my experience (and the solution) in the following thread. (It was triggered by the TCP-MSS clamping issue, but the underlying cause and solution is the same, namely poor integration between the load-balance feature an the rest of the VyOS routing features.)