In this case, try to create a calculated column. If the real data is not as cleaning as the sample, you may need some extra data cleaning work(not in Power BI). The best option would be classifying the comment when inputing, eg using some droplist having the themes and save the themes along with comment.
themes = SWITCH ( TRUE (), TRUE ()&& SEARCH ( "manager", Table[Comment],, 0 ) > 0, "manager", TRUE ()&& SEARCH ( "infrastructure", Table[Comment],, 0 ) > 0, "infrastructure", TRUE ()&& SEARCH ( "R&D", Table[Comment],, 0 ) > 0, "R&D" )