I found a bug in the "Achievements" section. How do I report it to the developers? It's more just an oversight in how an achievement was defined, not exactly a software bug per se.
It's the "Swords vs Machine guns" achievement. The description says, "You defeated modern units using only medieval and ancient units. However, the victory I attained used 1 Air Force unit to amplify the strength of my medieval units. I suspect the bug happened because I used Himeji Castle to sacrifice my Air Force unit in the war, which technically meant at the end of the war I didn't have the Air Force unit anymore. So I think that shouldn't have given me that achievement, but I can understand maybe why it did since at the end after using Himeji Castle I only had medieval units leftover. No big deal, just want to bring the odd issue to their attention.