Great job OP, about the bans, my friend was banned after botting for 2 weeks straight (with breaks, but the same activity and didnt play legit within those 2 weeks).
I belive the reason you got detected is the activity, real players, will randomly do new things, such as rotate the screen , examine items, have random AFKs, talk to people, open quest guides in-game, open world map, walk places and talk to people.
Whereas the bot is singularily focused on its one objective, in this case mining tin.
I think if you had moved to a different mine, a different ore, and or botted less hours per day, such as 4-6 hours per day instead of 10 hours per day, you may of not been banned.
Also I agree, instead of Randomization, we should isntead focus on 'Human Timing/Human Emulation'. Because as you said, random delays +/- 10% variance become easily plotted onto a graph.