No, you shouldn't have to add the static route. The problem here the LAN network the TZ180 is reporting to the tz210 is different than the destination network the 210 has configured for its SA. I don't know why. At this point, to me, it would seem a call to sw support is in order or an upgrade of the appliance. The interface of the 180 seems extremely outdated...likened to the SOHO OS from several years ago.
It should work, I don't know why it doesn't. I feel like we've tried everything. Seems simple the solution, but I'm just not seeing it.