The R has history with injectors, some can lead to melting an engine so I wouldn’t ignore it.
as @Msportmanhas eluded to, it’s often better to take the vehicle to a specialist with a good reputation to have it checked out….especially if injectors are suspected.
you can get a 2nd hand fuel rail c/w lines and injections but your spending cash without knowing it’ll actually fix the issue. 4 new injectors will cost £600-£700 without labour, and new manifold seal and cost. If close to RetroRemus I’d definitely go there.
i had a leaking injector with my mk7.5 R and had an interesting period trying to troubleshoot it, long story short take to the specialist, pay the money and pay it once, learn from it and move on.
keep the old injectors, send them away for testing, and have them redressed so next time you won’t have the costs of purchasing them.