You need to use a coolastart cot is HOAT (Hybrid Organic Acid Technology) compliant. That's what Triumph states in the manual. Mixing coolants that aren't compatable may cause bad things to happen with the cooling system like gelling of the coolant. Zerex G-05 is compliant along with numerous others.
I had to sift through many types of coolant until I found some concentrate for diesels that had the HOAT label. Since I have to park my bike in an unheated shed, temps can often drop to -40F so the last thing I needed was a cracked block. The standard coolant that Triumph supplied was only good for -32F. Drained almost 2 liters of original stuff and added the concentrate. Did this last year and have had no freezing or cooling issues since then. Prevention is the key. Do the research up front. The coolant Triumph sells with their logo is almost impossible to find.