We got some pretty complicated HTML/JS/CSS up and running and nicely integrated (js talking to blueprints and vice-versa) in under 30mins. It's fully backed by Epic now through a grant.
It handles video and audio nicely as well. There's little reason to consider using the inbuilt UI stuff when it's so easy to leverage existing HTML skills to build it out.
A few of us from the Valve development community, EA, and Blizzard wrote this as a side project.
http://www.andrewmcwatters.com/grid/ https://github.com/Planimeter/grid-sdk
Does it support cross-platform releases to consoles, mobile, and PCs?
LÖVE's team moves really slowly though, and we release updates on about a weekly basis. We'd eventually like to move off of them but keep a similar framework API for people to migrate away from.
I imagine this will gradually improve, but for now it's really not an appropriate engine for that class of games. Anything from LÖVE to Unity works much better.