In Plasma 5.9.2 (Info Center: X-Server)

'Vendor Release Number' gives:
'11,804,000'

But, it has to be:
'1.18.4'

Because:
$ /usr/lib/xorg/Xorg -version 2>&1 | grep [Ss]erver

X.Org X Server 1.18.4
xorg-server 2:1.18.4-1ubuntu6.1~16.04.1 (For technical support please see http://www.ubuntu.com/support)

And:
Presumably, it's not a "Vendor Release Number", but a "Vendor Release String".
If I'm right, then please rename this property accordingly.

And:
Directly below this, we find:
Version Number -> 11.0
a) I think, this is a version _s_t_r_i_n_g_, too. Not a 'Number'.
b) This is not the server version. This is the X Window System _p_r_o_t_o_c_o_l_ version.
Please rename this accordingly, too.