I can't read Japanese either but playing DMM is fine. You get most of it from playing Nutaku first. The rest can be gleaned via research on the DMM Aigis wiki and using Google Translate. Its not perfect but not hard to work out. It does make playing on DMM more a pain in the butt however the pace the game moves and variety makes it almost completely different to Nutaku.
One thing I have found is finding help videos is trickier so I generally don't bother with them. But you have more regular free SCs so the margin for error can be greater. Also your team builds a lot faster with better quality units. As a free player on Nutaku that margin isn't there due to lack of regular SCs and unit quality is a lot lower.
The game can't last forever. By its design we are already seeing that new units are merely variations on things other units can already do but in a different way or power creep goes up a notch. While power creep isn't so bad because there is no PvP it can kill a game over time.
In a way 2nd Awakening is part of that but its also a way to prolong longevity and hopefully open up a new end game for the players who can do it. If this means new hard content across the board that is good but it could also mean the game will end (when the money dries up) with newer players not even coming close to trying it.