I would fix it unless I never filled the tank above about 3/4. Anywhere near full and there is going to be "slosh" around that fitting, and water leaking into the interior, even if just the bays, is never a good thing.
In the picture on the left, the fitting appears to be accessible, but the right looks blocked. Not sure what I'm looking at in the right photo, but is that a hole in the side of the fitting? If so, the best fix is to replace it, but if you can't get it out, a plumber's epoxy ought to work. Make sure its rated for use on ABS fittings (that looks like ABS to me).