Congrats on being in a remission (quiescent phase of a chronic inflammatory response)!
There are a few variants of UC that present in only the rectum and Cecum/Ascending colon. So, no, it is not a pancolitis now and it is not a crohn's disease (due to a skip lesion).
Inflammation within the cecum at the junction of the appendix
opening: "Appendiceal orifice inflammation (AOI) is a common ‘skip lesion’ in patients with ulcerative colitis (UC)." https://www.ncbi.nlm.nih.gov/pmc/articles/pmc4071881/
The “cecal patch” in patients with ulcerative colitis
UC is a disease that classically begins just inside the anorectum and extends proximally (continuously) for a variable distance in a circumferential and uniform fashion, without “skip” areas. There are 2 types of segmental inflammatory change, however, that may be seen in patients with UC, and that may lead to confusion with Crohn's disease: backwash ileitis and the cecal patch; neither affects the course of the colitis.
An isolated cecal patch of inflammation, as in the present case, is present in many patients with left-sided UC or proctitis/proctosigmoiditis. We have learned that cecal inflammation may be part of normal cecal health, and that the cecum has a higher percentage of eosinophils, Paneth cells, and laminar propria inflammation than do other areas of the colon. The important lesson: don't diagnose Crohn's disease just because you see a patch of cecal inflammation in a patient with distal colitis. Pythagoras believed he could judge the height of Hercules from the length of his foot (ex pede Herculem), and from this it was extrapolated that from a sample one can judge the whole. This adage certainly is not evidence-based, and should not be used to rationalize judgment of the nature of colitis from the presence of a cecal patch. https://www.giejournal.org/article/s0016-5107(08)01639-8/abstract