Your assessment is fair. There are a number of manual pieces to pull this off, as you've noted. I'll make a note of your suggestion. When we have design discussions about this feature, we can reference this thread.
Rightedge is great for automating strategies with single contract orders, but it's not so good to trade spreads etc.
Currently, trading a combo involves submitting independent orders for each leg, which exposes the trader to execution risk and is awkward for placing limit orders since all the pending orders have to be reconsidered on every tick.
I don't know if this is the optimum way to handle it, but I would envision within Symbol Information a new Asset Type of "combo" with fields for component contracts , ratios and a flag to indicate whether this is sent to the broker as a 'combo' or sent as individual components.