In short then, this is the way I see it.
If Wasps can't refinance the bond, the primary security is the 250-year head-lease held by ACL (for the purposes of this, ACL and ACL (2006), who actually hold the lease can be considered the same).
One scenario is that the bond holders take ownership of the head-lease and sell it to recover as much of the debt as possible. They could sell to whomever they choose, obviously.
Perhaps the other scenario is that ACL goes into administration. If that happens, the head-lease could revert to the council, but it leaves the bond-holders completely out of pocket so I'd fancy that results in a court challenge.
Either way though, if refinancing fails, you'd have to think that the head-lease for the stadium ends up in someone else's hands - that was the whole point of offering it as security. It's an enormous blow for Wasps if that happens, I think, because they're reliant on the income derived from the lease.
For CCFC, I still think the overall picture here would be positive. Whoever takes over the lease is still going to want CCFC to play at the stadium. It might even be that CCFC would try to buy the lease themselves at a discount. The only people who really lose are Wasps, because at best they become tenants too.
Last point: If refinancing was straightforward, it would have been in place long before now. The deadline has been known since the bonds were issued. The fact that it's been missed, and the late filing of accounts all points to Wasps being under serious pressure. Anyone who thinks otherwise is kidding themselves.