[ESMA 35-43-349 MiFID II Q&As on Investor protection, Ch. 4, question 2]

Yes. Article 16(6) of MiFID II states that firms “shall arrange for records to be kept of all services, activities and transactions undertaken by it which shall be sufficient to enable the competent authority to fulfil its supervisory tasks and to perform the enforcement actions under this Directive, Regulation (EU) No 600/2014, Directive 2014/57/EU and Regulation (EU) No 596/2014 […]”. Article 16(6) has a general application and does not provide for exclusions of particular types of transactions. SFTs are therefore inside the scope of the MiFID II record keeping requirements.