I didn’t know of that Google Docs spreadsheet. What I used are the formulas from here:
They give a bit less exp for some levels, but most importantly I got the last level off by one. I think your spreadsheet is better.
Still, for that 9 10x feeding they’d have to use 10 heroes for the last Tier 1 feeding when 3 might’ve been enough.
Anyhow, whether it’s 0.3% or 0.4%, that Aeron was very unlucky.