I'm asking for the graphic designer's response to our questions before deciding whether to ask the project to consider changes. Here is my understanding of the outstanding questions:
- re: Your comments about kerning...
I totally agree that you have detected a problem. If the designer says, "No, I purposely made this kerning choice." then the project admin's are free to make a choice for change or not.
- Bottom vs middle align for wordmark/tagline: This appears to be a deliberate design choice. It's up to the client (i.e. the OpenWrt project) to say whether they like it or not, and since the choice has stuck I would assume no one else in the project has objected to it.
I suspect no one in the project actually tried to put the logo into service. When I did, the "too-lowness" of the wordmark jumped out at me. That's why I want to get the designer's thoughts.
- Padding around logo: The "x" measurement for each variant is derived from the design itself. I don't think it would be reasonable to ask the designer to redefine it in a way that makes it easier to compute using a formula. It's also not necessary since the specified padding is only a minimum; make the actual padding at least a quarter of the full height of the logo variant and you have satisfied the minimum requirement.
"Just put more padding around it..." doesn't make a strong graphical design standard. To the contrary, I believe it is reasonable to ask the designer to come up with a simple rule such as, "Make the padding X% of the .svg's height." The fact that you and I (who are both fairly careful about graphical appearance) have spent so much time on this question means the designer is not being sensitive to their customer's (that is, our) time. See also  below.
In all these cases, I would like advice from the designer responding to our observations. Only then can the OpenWrt admins decide what to do. Thanks again.
 Here is my understanding of the measurements, based on a close reading of page 4 of the logo guidelines. I willingly accept any corrections if I have missed something:
(logo over the wordmark) The X height is measured from the top of the "fan" to some indeterminate distance below the bottom of the "O" (or the top of the "OpenWrt" wordmark. But their spacing is not specified.
(wordmark alone) The X height is measured from the baseline of the wordmark to the top of the ® symbol. The ® seems to be vertically centered on the top of the "O", but its font size seems to be considerably reduced from that of the rest of the wordmark, so its font size is unclear.
(logo beside wordmark) The X height is measured from the baseline of the wordmark to the top of the "fan". It is uncertain how those objects relate to each other, or how to derive the X height.
(logo alone) The X height is measured from the bottom of the "O" to its top. If that glyph is actually a circle (I think it is), it is straightforward to compute the X height using the width of the .svg.
TL;DR For this third question, I would be completely content if the designer would say, for each of the four, "Set the padding to a minimum of X% of the height of the .svg." That would eliminate any confusion.