ISA are auditing standards so are relevant to how audits are to be conducted.
IAS and IFRS are accounting standards. They are relevant when you need to check that the FS are compliant with those standards or identifying a risk that they are not. So, for R&D the risk is the revenue/capital treatment and you need to know what conditions need to be met for capitalisation, and compliance with those conditions will have to be addressed at some point in the audit.