Our sales team works in tandem with a Sales Engineering team of 3 (2 + their manager), we sell a very technical product and the SE team presents demos, takes the lead on POC's, and are generally invited on most calls just in case.
All the SE's have been here at least a year but can't do more than an initial demo on their own. They work as a group after the first call (teamwork is great but kinda weird to have to invite an entire team to a straightforward POC kickoff) and after the first demo the manager of the team usually has to step in on any follow-up demos/Q&A calls/etc. which means that the customer now has a new technical point of contact who has none of the context from the last call and often has to re-explain things.
They're all very smart and we absolutely need them to close deals, but the way they do things makes our whole sales process disjointed and confusing, not to mention the two more junior ones struggle to answer a lot of questions, don't consistently give good demos, and things like that.
I'm no sales genius or technical expert myself so how do I let them know they need to be better without upsetting/insulting the people I need to close deals?