We'll soon put a section into the FAQ to deal with the question whether to use WDL or lite-C after upgrading to A7. The short answer is "it depends".

Old WDL projects can be continued in WDL. The only exception is when you want to use particular lite-C features, like structs. A few new engine features are also lite-C only; if you want to use them you need to convert your project to lite-C.

New programming projects should always use lite-C. It does not make any sense to start a new project in an old language.

If your lite-C project is "still very buggy", better go and fix those bugs. Lite-C is finished since a year, so there's no need to wait for new versions. There will be new lite-C features, but they won't help you with bugs that you already have with the current version.