I believe the verses were composed by either Rama III, Rama IV or Prince Vajirañāṇavarorasa. Whoever it was, he didn’t supply any translation for them. In modern Thai chanting books where there are accompanying translations, some have taken Sūriyo and Candimā to be the solar and lunar devas of these names (as in SN 2.9 and SN 2.10), while others have taken them to be the King and Queen of Thailand.
SuttaCentral