should we add a 5th component of minerals/trace elements??? Maybe. Most peat moss base mixes have lime and gypsum added, I’m not sure anything else is needed. But you can add more stuff like granite dust, azomite, greensand, etc. if you want.
If you’re starting with pure peat moss or coir you will definitely need to add some lime to balance pH, and other sources of minerals. The base peat and coir mixes from companies like Promix will have lime & gypsum in there.