At https://templates.onlyoffice.com/ there is a statement that ONLYOFFICE templates are absolutely free to use.
As an OnlyOffice user I would appreciate it if those templates would be licensed under specified free license like CC0 to clarify permitted usage of them. I suggest CC0, because it will allow using templates without attribution which may be unprofessional in some cases (e.g. in the end of SLA contract of which there is template).
Suggested change:
Replace „ONLYOFFICE templates are absolutely free to use.” with:
„ONLYOFFICE templates are absolutely free to use without any condition, under CC0. Read more at: Deed - CC0 1.0 Universal - Creative Commons ”