Commandos acting as instructors for cadre missions works okay for small forces training as insurgents or troops employed in asymmetric warfare.
The Commando Company in a Marine Regiment I believe only has an establishment of 88 Commandos, and there aren't that many regiments available. So 88 instructors aren't going to train a planetary army.
I would encourage you to examine the Special Forces ODA, ODB and ODC Concepts.
ODA ( 12 Man Team)
"The primary operational element of a Special Forces company, an Special Forces Operational Detachment A, also known as an "A Detachment" or "A-Team," consists of 12 Special Forces Soldiers: 2 officers, and 10 sergeants. All team members are Special Forces qualified and cross-trained in different skills. They are also multi-lingual. The A-Team is almost unlimited in its capabilities to operate in hostile or denied areas. A-Teams can infiltrate and exfiltrate their area of operations by air, land, or sea. An A-Team can operate for an indefinite period of time in remote locations with little or no outside support. They are truly independent, self-sustaining "detachments." A-Teams routinely train, advise and assist other US and allied forces and other agencies while standing by to perform other special operations as directed by higher authorities. All detachment members are capable of advising, assisting, and directing foreign counterparts in their function up through battalion level.
Capabilities of the highly-versatile A-team include: plan and conduct SF operations separately or as part of a larger force; infiltrate and exfiltrate specified operational areas by air, land, or sea; conduct operations in remote areas and hostile environments for extended periods of time with a minimum of external direction and support; develop, organize, equip, train and advise or direct indigenous forces up to battalion size in special operations; train, advise and assist other US and allied forces and agencies; plan and conduct unilateral SF operations; and perform other special operations as directed by higher authority."
ODB
"The Special Forces company headquarters, also known as a Special Forces Operational Detachment Bravo, "B Detachment," or "B Team," is a multi-purpose C2 element with many employment options. It cannot isolate and deploy Special Forces teams independently without significant augmentation. An Special Forces Operational Detachment Alpha ("A Team") cannot deploy or operate without the support of the B Team. The B Team consists of 11 personnel and is the headquarters element of the Special Forces company. It acts as the command and control of the A Teams within the company. The B-Team establishes and operates the Advanced Operational Base (AOB). The B Team can and does: Plan and conduct SF operations separately or as part of a larger force; train and prepare Special Forces A-Teams for deployment; infiltrate and exfiltrate operational areas by air, land, or sea; conduct operations in remote areas and hostile environments for extended periods of time with minimal external direction or support; Develop, organize, equip, train, and advise or direct indigenous combat forces up to regimental size in Special Operations (SO); and train, advise, and assist other US and allied forces and agencies."
"The Special Forces battalion headquarters, also known as a Special Forces Operational Detachment Charlie, "C Detachment," or "C Team," provides command and control, and staff planning and supervision for Special Forces battalion operations and administration. The SFOD-C plans and directs Special Forces operations, provides command and staff to operate a Forward Operating Base (FOB), and provides advice and staff assistance on employment of Special Forces elements to joint SOC, JSOTF and other major headquarters."