The beam is there for the load bearing purposes andmight be enough.The wall below that may have been superficial or not.The beam should definately be continuous. A standard wood beam should be approximately 1″ per foot of length of the opening.If it is a beam of some kind of engineered lumber product it could be a little less. You could take some drywall off and look at the material to find out what it is and then check span tables accordingly.It definately matters what is on top of the beam, structurally speaking. If you have somebody look at it that should be taken into consideration.

Even if the beam is of appropriate type and size,
there is a possibilty that previous owners removed a sheer wall below the beam . It is a little harder to determine if one should be there or not. You probably know, sheer walls resist racking in an earthquake. A good contractor or structual engineer could try to determine this for you.It might require taking some drywall and flooring out, if good prints can’t be found. Maybe you could get repair suggestions in writing and negotiate a credit to resolve the problems.

There are other possibilities involved, of course, so just take this as food for thought.Check permit history ,maybe, but not likely, permits were pulled for the modifications. Be careful even if you find permits because people are known to play tricks on inspectors. They will do a lot of the work before or after the inspectors involvement.Do a complete forensic study.