If I have {vizkope guildmage} out and activate his second mana ability can I also copy it with {strionic resonator}?
No. That, my friend, is an activated ability. A triggered ability begins with "when", "whenever", or "if". Activated abilities will have a cost that requires being paid, like the guildmage.
Vizkopa Guildmage's second ability creates a delayed trigger. If that trigger goes off, you can copy *that* with the Resonator.
Thank you