Alpha Moving engines more to the back would also make it harder to strafe, which is fairly important for wall designs, you can easily fit flak even without moving engines more backwards, usually walls have enough rotational thrust with the front/back thrust located on the sides.
Also those boost engines are not very permanent, they will run out of power all the time because a boost engine connected to an engine room uses more power than a reactor can provide. I would also say that the engine modules are very much overcrewed, you don't need more than 2 quarters for that, in fact 1 quarter and 1 bunks for each engine room should be plenty.
The reason most walls have flat front is not because it's "easier" (although that might be one of the factors) but because strafing and dodging makes shots "glance and spray" over the surface instead of being focused onto one spot. Generally I feel like this ship is a little confused about it's purpose, does it want to be a fast wall and dodge to avoid fire? It's too unbalanced and not fast enough to do that, or does it want to be a more tanky wall (seems like this one to me)? Then some back protection is needed with at least partial armour. You can easily fit it there without covering all the engine no build zones. Generally with non-flat front you want your middle part more protected as well, it's too easy right now to get through the cannons and behind them.