Your interpretation is basically correct. However, “kapunoan” is not a common term and I think would not exactly translate to “your majesty”. “Kapunoan” is derived from “pinuno” (accent on “nu”), which means “leader”, hence, “masusunod kapunoan” would mean more like “your wish is my command, chief”. We use “your majesty” to address monarchs, and in Tagalog, we say that as “kamahalan”. “Your wish is my command, your majesty/highness” would therefore be, “masusunod, kamahalan” or “masusunod po, kamahalan”.
Also, “susunod” is “to follow”. “Masusunod” is “(something) will be obeyed/followed”. “Susunod ako sa iyo” = I will follow you/I am next to you (in line)/I will follow (obey) what you say. “Masusunod ka” = What you say will be followed/obeyed.