What is the ruling on being named with names such as Ma'soumah, Kamil, and 'Asim, and what should one do if they have been named with such a name and find it difficult to change it?

There is no objection to being named "Ma'soomah," "Aasim," or "Kaamil." "Ma'soomah" means protected or preserved, and "Aasim" is a well-known name among the early Muslims (Salaf As-Salih). "Kaamil" means a man who is complete in his experience and intellect. These meanings are relative, and we see no impediment to using these names unless they are intended for self-praise (tazkiyah) or if they imply such in the custom of a particular country. The dislike of self-praise is a dislike of tanzih (discouragement, not prohibition), so it is not obligatory for someone whose name is thus to change it; changing it is only recommended. As for forbidden names, it is obligatory to change them in official documents if possible, otherwise in daily interactions.