LDraw.org allows third party part in the LDraw Parts Library

[Eugen]

Your links are not working

Fixed links in my comment.

There is, it is stud26

Thanks for pointing.

But there are few cases that various software may not rule out for Third Party parts with "stud26.dat":

1. When in sotware its enable to show "Thin Lines" logo on sharp stud (stud-logo.dat), its expected for Third Party stud top edge would be sharp (i.e., stud26.dat) — its work in LeoCAD as expected.
   
2. When in software its enabled to show studs with a "Outlined"/"Sharp Top"/"Rounded Top"/"Flattened" (stud-logo2.dat, stud-logo3.dat, stud-logo4.dat, stud-logo5.dat accrodingly) logo, its expected that Third Party studs top edge would be rounded — this does not work in LeoCAD.
   
   1. The same for open/hollow studs in Third Party parts, as there is no open/hollow stud with rounded top edge but without logo to be used in Third Party parts.
3. When in software enabled to show "Hight Contrast" or "Hight Contrast with Logo" studs, its expected for Third Party high contrast stud (without logo in both cases) would be used too — this does not work in LeoCAD.
   

Screenshots (left part is a normal brick 3005 part, and right part is a modified according to Third Party part design style).