[css-conditional-5] Queries re font-technology support queries

The Conditional Rules level 5 spec extends @supports with new font-tech() and font-format() functions. In looking to implement these, a few minor questions have come up that I'd like to clarify/confirm.

(1) The syntax for font-format() appears to accept only keywords, whereas the format() function in the CSS Fonts @font-face src descriptor accepts either a keyword or a string. While I think keywords are preferable here, I wonder whether we should also accept the string syntax in @supports font-format(...) for consistency with the @font-face descriptor?

(2) The syntax for font-tech() accepts a single keyword identifying a font technology. In contrast, the tech() function in CSS Fonts accepts a comma-separated list of font technology keywords. Should @supports font-tech(...) similarly accept a list?

(3) A really minor issue, but I have found myself repeatedly writing things like @supports font-tech(features-opentype), and not getting the expected result because the correct keyword is feature-opentype (singular). To my mind, the feature-* keywords would read more naturally in the plural form (similarly to font-tech(variations)). Should we change them to plural, here and in CSS Fonts, before this is widely implemented and webcompat becomes a constraint?