Hello. You are right. Your right of way must be varied to apply to the new route, as the right will apply to the old route unless it is modified. You will have real issues when you come to sell if this is not dealt with. I suggest you speak to the neighbours and remind them that you have rights and these need to apply to the new route. They need to enter into a deed granting you rights over the new track and releasing rights over the old one. They should cover the costs of this. Land Registry will not do anything about your rights unless you do this. Best wishes, WB.
No - they would know that the land exchanged remains subject to your rights in law, even if changed on the ground. They don't check these thinfs, just register them.