We've tried, but we couldn't get it to work the way we wanted it to. We settled on just applying the config manually through the web interface. I did have some calls with authorized resellers prior to this decision, but they also couldn't help us figure out the real issue.
However, did you try the newest firmware? I've read some interesting things in the changelogs since we tried this, it might just work nowadays.
Btw: if possible, try using wireguard instead of ipsec. We switched over a week ago, and never looked back. Much faster handshakes, connection speed, and easier to setup. We didn't try to configure it using UCI yet, but like I said before, it might just work this time. It's worth trying!