PARA SF have trained with US Green Berets & Rangers however I dont think there's been any training with Tier 1 Units like Navy Seals/ Delta force or even British SAS/SBS?
That's because most cross training and/or joint exercises are typically conducted with direct counterparts. This is for a reason. You don't send personnel from our 91 Infantry Brigade (IA's amphibious infantry) to train with, say, troops from the US Army's 10th Mountain Div. You send them to train with USMC.
And same applies when looking at it from their perspective, they won't send their Army just because we sent our Army, they'll look in their inventory for what units they have that are suitable for a given exercise and they'll send them, in this case, Marines:
The same is more or less true when talking about training with JSOC units. The Tier-1 SOFs typically train with their counterpart teams from allied nations, like seen here in a joint ex with French Tier-1 operators:
This doesn't outright mean Tier-1 forces of US have never been in India or trained alongside certain units with roles that lie so far outside the 'typical' SF subset like counter-terrorism or clandestine action (and yes, that is different from covert action). They certainly have. But the fact remains, that India at the moment does not really have a Tier-1 counterpart/equivalent.
If the American SOCOM structure were to be superimposed on the Indian SF scene, we'd only find units which can fill what they would consider Tier-2.
The units under AFSOD are (or at least will be) the closest thing to a Tier-1 force that India would get. Mayhaps sometime in the 2020s, we'd get to see some regular AFSOD-JSOC interactions & exchanges, and ones which will actually manage to make it to public domain (not least because the nature of such exercises from the CT subset like tubular assaults, clearing public infra etc. aren't anything to be completely classified).
