Yes that's a biggest issue in any small room so you put speakers to the wall behind them as the next best thing to do. In this case they are far from it and let it stay like that instead making a bigger problem out of it (ISO 3382-1 early-to-late arriving sound energy, problematic in lows particularly). And make direct one stand out more. A room mode refraction is always present and first fundamental and following two (it's harmonics in the large part) will remain the same if you rotate 180° it's length influenced. Again you do best you can and use it for reinforcement not killing it entirely but making energy brust (spectral in waterfal) there more in line with smaller other room influenced one's. You use combination of VBA with negative responses in FIR wav and then PEQ the rest (to 1~3 KHz as good you can and Q filter is relevant factor of 50) and if need be slope down highs future more. That's about it.
Edit: you can play with the phase after that but if done correct so far you won't mess impulse response (decay, pre ringing, mismatch between L & R as you do the match and both FIR and PEQ are done minimal phase...) in the first place so that's more mandatory or if such problems occurred.