The mezz lender's access varies by deal, and your instinct to be curious about it is well-founded because it matters a lot.
In a well-run deal, the mezz lender reviews the full senior loan documents, or at minimum a highly detailed term sheet, before committing. They need to see the cash sweep language (that is the clause that diverts property cash flow to the senior lender instead of letting it flow to equity or subordinate lenders), the default triggers (the conditions that let the senior lender declare the loan in default), and the yield maintenance schedule (the prepayment penalty formula that makes it expensive to pay off the senior loan early). All three affect how much control the mezz lender actually has and when they might get squeezed out.
What complicates the picture is timing. Senior loans often close on a parallel track with subordinate financing. If the senior is genuinely still being finalized, the mezz lender may be pricing off a term sheet and relying on intercreditor agreement language to protect themselves later. An intercreditor agreement is a contract between the senior and mezz lenders that spells out who gets paid first, who controls a default, and what rights the mezz lender has to cure a senior default before losing their position.
The risk you are sensing is real. If the final senior docs contain materially different sweep triggers or default definitions than the summary the mezz lender saw, their pricing may not fully reflect what they signed up for. I would ask the fund manager two things: whether a final intercreditor agreement is in place, and whether the mezz lender has signed off on the actual senior term sheet or only a summary.
Treat this as a starting point for your own diligence, and consider involving a real estate attorney before going further.
What is the fund structure here, equity or debt, and do you know whether the mezz quote is already binding or still indicative?