Yes, Entocort is a steroid. And yes, steroids like prednisone can contribute to peptic ulcer disease. But Entocort is quite a bit different from prednisone. Budesonide, which is the steroid in Entocort, has a high first pass metabolism, which means that most of it acts directly on the bowel and, compared to prednisone, does not act on the entire body. This means it generally has far fewer side effects than prednisone. For example, rates of peptic ulcer complications are far less with Entocort than with prednisone.
As for its use, it's true that it's generally used for a flair and not for maintenance. However, it's a bit more complicated than that. For example, you say you're in remission, yet you have inflammation in your right colon. So, actually, you may be in *symptomatic* remission, but you're not in complete remission (defined as absence of symptoms PLUS absence of any inflammation). For some people, that's good enough, and no change or addition to their medical treatment is needed. For others, depending on the doctor and the patient's opinion, they may decide to add/change meds to try to knock down all inflammation, in order to get a handle on things before further damage is done to the intestinal wall. So whether or not to change/add meds is up to you in consultation with your doctor; there is no clear cut right or wrong answer.
And what's more, studies are showing that Entocort can be used for short term treatment of flairs (a course of 8 weeks or so), and for use in maintaining remission for an additional few months. It is considered safer for long-term use than prednisone. So, really, you could think of it as falling somewhere between a short-term usage drug like prednisone and a long-term maintenance drug like Asacol, Pentasa, or imuran or 6mp. Think of it as a medium term maintenance drug.
Now I'm not saying it's a must that you go on Entocort. I'm simply saying it's a good option to consider if you decide you want further medical treatment of your inflammation.