They did constantly trained with american sof for few years now.
Heck their new gear is direct result of that.
MARCOS usually is seen with Foriegn Ex in Multinational Ex - APAC/AFrica etc
We have done these ex with Asian Countries, South Africa, South American Countries - these Ex are usually diplomatic in nature - value accretion is low.
MARCOS has done jt ex with the SEALS ( like ex Sangam) and USMC on a handful of ocassions - again few days / 1 week type durations - more Diplomatic / FID in nature to build "interoperability"
They dont really provide the "upskilling" you seem to hinting at. - Unless you have other info?
At best its Exposure - and IMO the higher educated Officer Cadre see the value of the new PPE etc and since their budget outflow requirements are low its easy to do.
NOTE - alot of Indian Naval Ships (and by default the Ship Command) spend time on foriegn shores and have been getting exposed to their Global Counterparts. Alot of MARCOS forward movement can be chalked up to that as well.