in the shared Dropbox I created a folder Tongan, which contains a file called "tongan-lg.pdf". On pages 14-15 you can find further details about the orthography. Long vowels are represented in Tongan orthograpy by use of a Macron ("long vowels, as in màlò"). Meanwhile definiteness is marked by stress, which is is written in Tongan using a rising accent ´ following the vowel ("The fakamamafa pau or defi nitive accent falls on the fi nal vowel of a word and designates defi niteness, as in tangata ́ (the man).  An example of the difference that the defi nitive accent can make is this: ko e tangata means “a man” but ko e tangata ́ means “the man”.")

Logically this leaves us with a sequence ā´, which should be confirmed by an expert on the language.

Meanwhile Wikipedia informs us that "Although the acute accent has been available on most personal computers from their early days onwards, when Tongan newspapers started to use computers around 1990 to produce their papers, they were unable to find, or failed to enter, the proper keystrokes, and it grew into a habit to put the accent after the vowel instead of on it: not á but a´. But as this distance seemed to be too big, a demand arose for Tongan fonts where the acute accent was shifted to the right, a position halfway in between the two extremes above. Most papers still follow this practice.".

This is why I commented this in column J "Possible variant of ā´ ". I hope this clarifies the situation.

Best,