There seems to be a behaviour of this software that is not obvious, or in the tutorials.
Sorry I don't understand what you mean by this, there are thousands of people using Vectric software without any issues, I don't personally do anything that requires a particular degree of accuracy but have read posts from users that do.
As Adrian has said this is really a user to user forum, if you would like Help directly from Vectric then you will need to contact then directly, from my own experiences they are very helpful, they are based in the UK so there may be time differences to consider if phoning
http://www.vectric.com/company/contact.html