Basement beam concern
The beam support using a pair of 2x6 posts is slightly unusual, but not a problem. The screw jack supporting the beam in the first picture may be an issue, because it does not look to me like it is a permanent rated support jack. It looks like a temporary support jack. You may want to check the manufacturer plate on the jack, and verify that the support is in fact rated for permanent installation.
As for the beams not extending all the way across the joist, that is poor practice, but not likely to be a serious problem. Possibly more important is the fact that the third 2x10 (or whatever size that joist is) does not appear to be adequately attached to the middle piece, based on the gap between the pieces. This could be remedied easily by nailing or screwing the pieces together. If you decide to go this route, clamp the pieces together before nailing or screwing to make sure they mate properly.
If there are already nails or screws in place, and that gap is as large as it looks, you may want to remove the fasteners first, clamp the boards, then reinstall.
As for the adequacy of the beam, without knowing the loading on the beam, it is not possible to determine if 3 pieces of 2x6 are adequate for the application. If you are concerned, you may want to hire a structural engineer to look at the house and calculate the load on the beam.