When dialing in a pour over, what factors indicate a change in water temperature might be necessary? I’ve been experimenting with my v60, EK43, refractometer and variable temperature kettle. I understand somewhat how grind size, water-to-Coffee ratio, agitation etc. affect extraction, but I am unclear on the role water temperature plays. I’ve heard 195-205 F is ideal slurry temperature, but how do I know when I might need to make a change in water temperature?
Agreed with the above answer by Jason: it's about taste.

That said, of late i have been surprised by how effective for extractin Scott Rao's 97degree C is for a pour over[link].In particular it seems that central and south american beans need the temp to get out the flavour - african's less so but still work in that range.

But to your question - a more specific mapping of flavours:

Matt Perger has a super chart to map when temp may come into play based on what you're tasting and how to tweak it. (2)