The official policy in Belgium is knopaccordeon (button accordion, meaning here in Belgium chromatic button accordion). Officially they did not specify Do1 (C-system) or Do3 (B-system), because of the differences between Hubert Kicken, Roger Eggermont and Jules Willems.
So there is some degree of freedom in choosing the CBA layout.
The Music Conservatory of Antwerp played an important role, and also the Lemmensinstituut in Leuven.
As a first year student at the university, I had to write a paper on education and pedagogy. I choose the organisation of accordion education in Flanders, and had a personal interview with Roger Eggermont and his assistent Ludo Mariën, back in 1990/1991. The decision in Belgium for CBA was actually a follow up of the international accordion conferences decisions, I have been told by E. Flecijn, one of my accordion teachers. The intention was to set an international standard for the right hand layout, the bass layout being more or less standardised as international standard bass.
(Most people write international standard bass, but in fact the spelling is international standard bass. Standardisation like in ISO. )
School and education matters are regionalised in Belgium, no longer at the Federal level . So there is a different policy between Flanders, Wallonie, Brussels. (And the small German community in the eastern part, they have some autonomy).
(By the way, diatonic accordion G/C system has also been institutionalised in Flanders for some years now. But they fall under the Folk Music departments. You can also follow diatonic accordion courses in some public music academies or schools.)
From 1990 until early 2000s (with a pause when I was a university student) I have followed accordion courses in 2 public music schools with: Eddy Flecijn, Philippe Thuriot, Bianca Francken, Conny De Merechy.
And in those days I have spoken with every possible accordion teacher in Flanders at masterclasses or recitals (when attending bayan recitals by Russians or Belgian accordionists).
The first generation of accordion teachers (the old school, musette players) were:
Jules Willems:
http://juleswillems.yolasite.com/
http://juleswillems.yolasite.com/biografie.php
Roger Eggermont:Tot in 1991 was de vermaarde accordeonist wijlen Roger Eggermont (1932-1999), toenmalig hoofddocent aan het Koninklijk Vlaams Muziekconservatorium van Antwerpen en bekend van radio en tv, zijn leraar.
http://www.brusselsphilharmonic.be/...ache=1&cHash=b358063fc26ac062eda9ec742b3e4407
The Dutch teacher Hubert Kicken in Antwerp:
https://nl.wikipedia.org/wiki/Hubert_Kicken
However, Eggermont was all into musette and popular accordion music.
It is only later that Ludo Mariën, Eddy Flecijn and Philippe Thuriot became the real first generation of classical accordion teachers in Flanders.
For Wallonie, Christophe Delporte of the IMEP is the teacher.
Eddy Flecijn:
http://www.eddyflecijn.be/
Eddy Flecijn is a very influential accordion teacher in Flanders, also a composer.
Ludo Mariën in Antwerp, Eddy Flecijn in Leuven and Philippe Thuriot in Ghent.
Ludo Mariën - The typewriter (L. Anderson)
Philippe Thuriot:
Philippe Thuriot, Accordeon/Accordion TENUTO 1991
Philippe Thuriot-Accordeon, Accordion/Goldbergvariations Nr 1 J.S. BACH
Christophe Delporte conducting an accordion ensemble at the IMEP:
La Classe dAccordéon de lIMEP
And these are a few members of the new generation of accordion teachers in Flanders:
http://www.accordeonsalon.be/
The Board:
http://accordeonsalon.be/Bestuur/index.html
These persons , born in 1980s and later, they are the very first to receive tuition from classically trained CBA teachers. So I expect the youngest generation to be the best educated accordionists.
Ivan Smeulders in a Kusiakov sonata:
Ivan Smeulders - accordion
An Raskin CBA from Belgium was a teacher in Holland:
http://www.koncon.nl/en/departments...l-music/accordion/teachers/689/an-raskin.html