Canvas+ was not worth the effort, (they worked hard to redeem themselves, and are starting to communicate more) however webview+ does not rely on a weirdly custom made browser engine but on the webview, and perform well on iOS8 it seems.
Basically you should not expect scirra to support any wrapper themselves, and cocoonJS are actually listening now so that may be worth a shot.
I stick with the non wrapped multiplatform export that is the web so I cannot help further. Was just explaining the current situation as I see it.