Just checked on my Mac and see the same thing you do. There was some discussion of this a few years back and I cannot recall the outcome.
What I see in AC 15 on 10.7.2 is that Myriad Pro is an Opentype / Postscript font but that Arial is an Opentype / TrueType font.
My system has an Adobe font called Myriad Web Pro which is an Opentype / TrueType font and its size and alignment are identical to Arial. (Size: "M" graphic heights equal each other and relative position inside the text handles is the same.)
I tried several other PostScript fonts (Arno, Chaparral, etc.) and they have the same vertical positioning issue.
So, either it is a system issue with PostScript fonts on the OS side not reporting their font metrics correctly to applications (ArchiCAD) or a Graphisoft issue of not positioning the font baseline properly for PostScript fonts...
Edit: PS I just tried Myriad Pro, Myriad Web Pro and Arial "M" characters adjacent to one another in Word (2008/Mac) and the baselines all align - and, strangely, there the M-size of Myriad Web Pro matches Myriad Pro, which is shorter than an Arial "M". Seems to me that if Word is able to read the font metrics, that ArchiCAD should be able to and that this must be a bug on Graphisoft's side. Will report after others chime in ... hopefully someone else remembers the old discussion of this same issue...
One of the forum moderators • AC 26 USA and earlier • macOS Ventura 13.2.1, iMac Pro 10-Core, Radeon Pro Vega 64