The new update coming in the next couple of days should solve the majority of the pathfinding bugs. I'm also a little surprised you seem to be encountering them so frequently? I've only seen reports of them occuring in very complex layouts, is your experience different?
With the two tile thing I'm generally deliberately restricting the players options of where they can place roads (Similar to when I have trees or houses blocking parts of the grid). I will try to chop off any sections of the grid that is completely unusable moving forward though.
Glad you had fun ;)