The reflection would remain proportionate to the direct sound, irrespective of volume level. That's why room correction systems set one-time filters rather than changing the correction dynamically. There's no need to do the latter. If you listen to everything at reference level, then you have no use for equal-loudness technologies. However, that's different from your original reason for not using it because it doesn't adjust for "room anomalies at different volumes". There's no room correction system that does that, nor are you likely to see one in the future that does.