If I understand this correctly you are having set to where the inkbird is the backup and the heater does the normally cycling on and off? If so that doesn't work for the 306A because of the continous heating alarm.Looks good, except I would set T2 to 81°F (from 80°F), the High Temperature Alarm to 82°F (from 80°F) and the Low Temperature Alarm to 75°F (from 74°F). This way the Cobalt heater shuts itself off when it hits 80°F (instead of the Inkbird) and you don't get a wailing alarm from the Inkbird if your temperature ever hits 80°F (it has to hit 82°F or drop to 75°F).
The Inkbird will always stay on if the temperature is above 76°F, and only turn off it the temperature hits 81°F. You'll get an audible alarm from the Inkbird if the Cobalt heater fails and the temperature drops below 75°F or exceeds 82°F. This gives you a ±1°F margin of error for the alarms on top of the ±1°F margin of error for the Inkbird temperature probes.