NALC guidance note L01-18 Financial Assistance to the Church, suggests that the prohibition on expenditure on property relating to affairs of the church contained in S8 of the 1894 Local Government Act still applies and as a specific restriction, it can be assumed to override all subsequent legislation, including the General Power of Competence. This has not been tested in the courts.
If this is the case, far from being an obligation to help, it could be considered an illegal payment.
Many rural parishes, including two of my own, contribute to the maintenance of their churchyards, whether open or closed, as highlighted by Counterpoint, reflecting their value as a public space and this has never been queried by the auditor, perhaps due to the obscurity of the original restriction in 124 year-old legislation.