I now have gotten miner and botanist to 50. I can definitely confirm that 80% success rate must be a translation error or mean something entirely different in Japanese.
80% in an FF MMO means 50% of the time you'll succeed 80% of the time. It's the SE random number coefficient. Other examples are 10% hq = 2% hq, 90% hq = 60% hq chance
Random numbers are a bitch.
I should finish my +1 relic for BLM today/whenever I do AK this week. I'm interested to see what changes they make to Myth tome farming in the patch tomorrow.