The foundations should be laid on the pilot initial type course. For the S76 that would be 10 full days in ground school, followed by 10 hours of dual instruction in the aircraft. Coming out of that training pipeline the newly minted S76 pilot should be in no doubt that you don't fumble about flying that thing manually in clouds, especially single pilot. Even a zoom climb to get visual above a layer. Use the tools you've been given in the way they have been designed. Sure, maintain your stick and rudder hands instrument flying when you have an instructor to monitor and check, for maintaining recency. In this case I suspect the accident pilot might not have had a sufficiently thorough type technical training foundation to rely on. And again, pure speculation, probably hadn't logged much crew room down time when the weather had clagged in with the RFM on his lap and refreshing memory from front cover to back. Everything you need to know about that autopilot is written in that book (and the Honeywell manual), and the practical application of that knowledge should be demonstrated in the aircraft on the pilot initial course.
And a more general observation. I am bewildered when pilots arrive on a $25K recurrent sim course not knowing aircraft limitations, and not knowing ECL memory items, not having seized any initiative to do an hours reading in the days prior to the course starting.