Annie, I'm a little late to this conversation, but would like to add a few thoughts.
First of all, you really shouldn't test a 13% flour with a formula geared for a 14% flour. To judge it fairly, you'll want to reduce the water to compensate for the lower protein. There's no exact science for this, but I'd suggest around a 3% reduction in hydration going from 14 to 13, seeing what kind of consistency/tackiness you get and then adjusting from there. A more protein appropriate hydration should go a long way in helping oven spring and browning.
From the research that I've done, depending on your fermentation time frame, adding more sugar doesn't necessarily give you more browning, at least, it may not give you the browning you were getting with the malted flour. I still have more research to do, but it looks like added sugar tends to get consumed by the yeast, especially in higher yeast, same day ferments. I know that yeast have a preference for different kinds of sugars (Peter would know more about that), so there may be a particular type of sugar that might survive longer than another, but, I think when browning is the goal, enzymes are the better choice. Annie, your bake time/previous flours produced a pretty golden brown delicious (GBD) end product. If these non malted flours aren't giving you the browning you're looking for, you can play around with adding sugar, but I think diastatic malt will go further. I also think you can improve your residual sugar by lowering your yeast a bit and extending the fermentation time. The diastatic malt adds enzymes and the extended fermentation time allows the enzymes in the flour to do more work. Refresh my memory, how long are you fermenting now?
It took me a long time to change my ways because it challenged my concepts of authenticity, but I would consider a bulk ferment. The poolish Scott recommended is most likely along similar lines, but depending on your workflow, this might be easier for you. I was highly skeptical for a long time, but now I'm a believer. Anything you can do to charge your dough with a good dose of pre-balling CO2 will go a long way to compensate for loss of oven spring when you drop the bromate.