Considering that companies fill HR vacancies with people from other disciplines, is there enough formal training for these people?
The scenario is changing for HR. While it is true that in some cases, HR roles are assigned to people from other disciplines, such instances are becoming increasingly fewer. Companies do look for trained HR professionals to handle HR roles. More often than not, if the role is assigned to a non-HR executive, the reason is not because of the quality of HR professionals, but the dearth of HR professionals.
Most companies do try to provide training to non-HR people through job-shadowing, nomination to HR courses and so on when they are given HR roles. In fact, this need has also sprouted some innovative partnerships between industry and academia. For instance, XLRI have two such partnerships, one with Accenture and the other with L&T, to conduct long-duration certification courses in HR. I think one of the challenges for the education sector will be to keep pace with the demand for HR professionals, both in terms of quality and quantity.