Right now I'm not clear on if we would need to model any additional information about your setup in MAAS to make this work for you, so I'm marking this bug 'Opinion' there.
We may still want to investigate if curtin can do a better job rendering the routes.
Can you explain why you are using a separate 'table' in this setup? I'm not clear on why that is necessary. It seems like you simply want a default route via one interface, and you want a static to one specific subnet via the secondary interface. (That is, you don't have any weird situations like an overlapping subnet, which would require a custom metric to be set, etc.)
Right now I'm not clear on if we would need to model any additional information about your setup in MAAS to make this work for you, so I'm marking this bug 'Opinion' there.
We may still want to investigate if curtin can do a better job rendering the routes.
Can you explain why you are using a separate 'table' in this setup? I'm not clear on why that is necessary. It seems like you simply want a default route via one interface, and you want a static to one specific subnet via the secondary interface. (That is, you don't have any weird situations like an overlapping subnet, which would require a custom metric to be set, etc.)