Your math must be incorrect, I think. In the Lenstips review of the PL 8-18, it says:
"In April 2017 the Micro 4/3 system was enlarged by another wide angle zoom lens, the Panasonic Leica DG Vario-Elmarit 8–18 mm f/2.8–4 ASPH. It was a very interesting launch. The customers got a device
with angles of view ranging from 62 to as much as 107 degrees and a very good aperture fastness as well. At the same time the lens is quite small and lightweight, with a filter thread just 67 mm in diameter."
The rest of the review is here:
https://www.lenstip.com/index.html?test=obiektywu&test_ob=508
I don't mean to say that 7mm isn't a fair amount wider than 8mm (since 1mm can be significant at this FL), but 8mm is pretty wide, and the advantages of the 8-18 over the O 7-14 outweigh the 1mm difference, IMHO.
Edit: I reread what you said. The Lenstips review may be talking about diagonal, so perhaps it is less than 90. But it wouldn't be much less, surely (and um, what's the big deal about 90?).