In my current game Resoln has swarmed one of my cities (a fortress, I believe) with multiple armies. They seem to have had around 4 armies at the start of their offensive, 4 units in each one. Out of four in each, one was well armed and equipped, the rest were either "militia" units with 0 defense, or spiders.

My city was defended by militia units only, one archer, rest standard guys with sticks, all in all 70 cumulative attack and 0 defense combined. 

Problem 1: Had the AI condensed its best units into one combined force they would have taken the city with no casualties during the first strike.

Problem 2: While the AI attempts to swarm by attacking with multiple armies in the same turn, after the first battle is over I get another message that the same city is under attack, but after clicking OK nothing happens. Trying to end the turn results in the button becoming greyed out, but the game does not progress. It is possible to save and continue to the next turn after reloading, but once the AI tries to attack the city multiple times again (with its 3 remaining armies) the same problem happens and a save/reload is necessary.