The route_list setting ^foo$:^bar$ $domain in a manualroute router does not work.

The first thing in a route_list item is a single pattern, not a list of patterns. You need to write that as ^(foo|bar)$ $domain. Alternatively, you could use several items and write

route_list = foo $domain; bar $domain

Note the semicolon separator. This is because the second thing in each item can itself be a colon-separated list of hosts.