By any standard the article is as complete as it can be at present - like other articles are meant to be.

'What we do know, is that surely that the article is 'incomplete' since we can only provide information on just two officers' It's an article about Islay Herald surely, not others?  

I am not sure what the Shirra has to do with this. Surely it's documentary, graphic, archaeological etc evidence that counts, not the unreferenced thoughts of the early 19th century Scotland's answer to Jeffrey Archer.

Though in one respect you are quite right. The article is incomplete - there is no reference to F  J Grant's little book - Islay is on p 11 of gthe 1914 edition - available as a pdf download online.

"The Scottish officers of arms formed an important part
of the Royal Household, and were in attendance on the
King on all occasions of state. Besides the duties enumerated
above, they were employed in accompanying embassies
abroad, making royal proclamation throughout the country,
carrying important messages of state between the King and
his subjects, and a summons for treason could only be
served by a herald or pursuivant.
As early as 1364 mention is made of William Pittolloch,
Herald; and in 1365, in the Great Seal Register, of John
Trupour, Carrick Herald (probably a mistake for pursuivant).
Lyon Herald appears in 1377, and ten years
later as Lyon King of Heralds. Rothesay Herald, officer
of the Prince of Scotland, is first mentioned in 1401:
Marchmont, a title derived from Marchmont, the ancient
name of the Royal Castle of Roxburgh, in 1436 ; Snowdoun,
derived from a part of Stirhng Castle, in 1448; Albany,
from the Duke of Albany, a title of one of the King's sons,
in 145 1 (he is called pursuivant, however, in 1447); Ross,
from the Royal Earldom of the same, in 1474; and tslay,
from the island of that name, in 1493. Other heralds are
also found from time to time, such as Ireland in 1498 and
Orkney in 1581.
Of the pursuivants, Carrick, Pursuivant of the Prince, who
was Earl of Carrick, appears first in the year 1365 ; Unicorn in
1426; Aliszaiin 1426; Dragancein 1429; Diligence in 1472;
Dingwall in 1479; Montrose, Bute and Ormond in 1488;
Falkland in 1493; Ireland and Kintyre in 1495 '> March in
1515 ; and Ettrick, "pretendit pursuivant," in 157 1.
The number of heralds and pursuivants became fixed at
The Heraldic Executive
six of each by the reign of King James VI., and continued
at this number till by the Act of 1867 their numbers were
gradually reduced to three of each as vacancies occurred.
The titles now [at the time of writing] in use are Ross, Rothesay, and Albany for
the heralds; and March, Unicorn, and Carrick for the
pursuivants".

FRANCIS J. GRANT, W.S.
Rothesay Herald
THE
MANUAL OF HERALDRY
A CONCISE DESCRIPTION OF THE
SEVERAL TERMS USED, AND CONTAINING
A DICTIONARY OF EVERY DESIGNATION
IN THE SCIENCE
(NEW AND REVISED EDITION,)
EDINBURGH: JOHN GRANT
31 GEORGE IV. BRIDGE
1914

p 11

Perhaps you would like to make the article less incomplete?