I think they were hoping to iron out the issues with HWA in a timely fashion and when they realized that wouldn’t happen they decided to add in more standards support and features to fill the void rather than wait until later this year (or next) to get version 12 out with stable, performant HWA. They’re encountering the same issues as Firefox and Chrome devs have, the same reasons why those browsers don’t currently attempt to render everything with the GPU.
As for aces in the hole, Opera’s never been one to publicly state what their future plans are except for the occasional labs builds and those don’t always pan out. It’s been almost 4 years since they first released a labs build with basic HWA for canvas. I’m surprised they aren’t using available tools (both Chrome and Firefox use ANGLE and Firefox is working towards using Skia) to make their path easier.