I've welded a couple BMW aluminum blocks like that, but not as close to the side bolt on the main cap. I'd be a little concerned about warping and weld integrity in that area since you should really pre-heat the block to 200 before you weld it like that, and then bring the temp back down slowly, but you might be just fine. It looks like they aluminum stick welded that or MIG welded it because of the weld look and splatter. If it's stick welded, it needed to be a pure DC machine with aluminum rod. If it was MIG'd, then I would question the penetration of the weld without preheat. Proper process is AC TIG with preheat and LOTS of cleaning beforehand.