Type size equivalents between 号 and "point"

For section 2.3.5 Considerations when Designing the Type Area | 版心设计的注意事项 | 版心設計的注意事項, the values for 号 and "point" have 2 issues:

1. there are more 号s in actual usage, e.g. in Microsoft Word (Chinese version) font list, there are
   大特号 (=63 pt)
   特号 (=54 pt)
   etc

2. the conversions between hao 号 and point (American point or DTP point, that's another question, though) are actually not unified yet, e.g. in Microsoft Word (Chinese version),

二号=22pt but not 21pt,
三号=16pt but not 15.75pt、
四号=14pt but not 13.75pt,
六号=7.5 pt but not 7.875pt、
七号=5.5 pt but not 5.25pt.

In hot metal era, the type size are also different from different type foundries. See the values shown in the book below, it just showed one of the variations. Some of the values go with Word, some of them not.

Although widely used, the settings of Microsoft Word are not correct due to its spec: the value of type size "should in multiples of .5 (such as 10.5 or 105.5)" (see https://support.office.com/en-us/article/Change-the-font-size-931e064e-f99f-4ba4-a1bf-8047a35552be?ui=en-US&rs=en-US&ad=US) so Word cannot set 三号 as 15.75 pt but 16pt.

How should we do such differences?