If someone had lymphoma wouldn't their lymphocytes in CBC be abnormal or the t cells and b cells? Bc that's where the lymphoma originates isnt it?

Not always. The complete blood count (CBC) can be normal in lymphoma. Lymphoma may or may not be detectable in peripheral blood. The cancer may be limited to the lymph nodes and bone marrow. In some lymphomas the lymphoma cells can be found in the peripheral blood (a so called leukemic phase).
No. This is a popular misconception. Malignant lymphoma cells seldom invade the bloodstream. If they did, they'd be leukemia. Most of your b-cells and t-cells aren't in your blood.