I think your focusing on the the wrong thing. A lot of times masters can't parse stockfish's positionally based inaccuracies. Maybe IM Pfren or one of the other strong players that comments sometimes like Inkspirit could answer this question in an educational way, but I'm not sure, and wouldnt expect a necessarily accurate answer from any class player that answers you. One thing I notice is that with the pawn on c3, the white knight is going to d2 and likely ultimately traveling somewhere where it will gain a tempo on the bishop, but I'm not sure that matters much. B4 and A4 could be a factor eventually perhaps? Black is probably playing f5 in this position to get play, and after he does so, f6 might be a natural position for the bishop (since white can't keep that diagonal from opening at some point). Your point about trading off the bishops is interesting, but that doesnt seem to be stockfish's plan from playing out the lines, and it seems like it might be time consuming as white would need to play c4 and maybe b3 first. But I'm not really convincing myself...this is why I don't spend time with inaccuracies. Its tough to learn unless you, after you think about it, you have someone like @impfren to help.
Am I correct as to why this move was an inaccuracy?
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Early game inaccuracies are what I’ve been focusing very hard on recently. I had one today and I think I realized why. Would like anyone’s input if I missed something deeper than stated below. Thanks!
thought process:
1. Black has dealt with whites pressure sufficiently
2. Black has no attacking moves as far as I can see.
3. Blacks dark square Bishop is his last piece on the bench, has a nice line it can move through, and it will open up his castle.
4. Moving it to D6 will crowd the d file to much for blacks queen and maybe a rook later if He gets one moved, so that leaves e7 or c5.
C5: More aggressive move than E7 but can be pushed back a bit from b4 which was setup from whites mistake playing c3 earlier.
White can open up his dark bishop and trade safely with blacks which would fix whites issue of being behind on his development.
E7: less aggressive but can’t be annoyed by pawns nor traded with whites Bishop leaving white 1 less option to open up.
Not allowing white to cause black to react to something will allow black to start creating an attack.
Reasoning: even though C5 appears to be in a stronger and more aggressive spot, it benefits white more than it hurts him and only gives him more options to fix his development and maybe get some lost tempo back. E7 prevents all of that while still maintaining the benefits of completing development and opening king side castle.