Retainer Venture Question

[Parawill]

For your actual situation, your retainer needs to meet the required gathering stat. Basically you need to give your retainer better gear.

Both retainers are maxed out at 25 for their assigned job. How do I break their cap?

You need to actually level your own gathering classes before you can max out your retainer's Botanist, Miner or Fisher level. So if you ever want a level 50 Botanist Retainer, you need to have your own Botany level at 50.