In current implementation, it seems that a newFontDescription is created and set for initial-letter's pseudoStyle. However, only size is considered, the other font related style is not. I think web authors may prefer have initial-letter keep its flexibility to set a font different from its surrounding text. This also mentioned in spec: https://drafts.csswg.org/css-inline/#initial-letter-properties as well. test case: http://codepen.io/anon/pen/AXkxbE
This test case works properly in Safari 15.5+. I don't believe there is further action needed here.