The question in that link is "I got a question. In Cavendish experiment was used lead in both of spheres. Can we repeat that experiment with balls made from stone or anything else. Because lead could be a byproduct of radioactive decay and by that emit ionizing radiation. And by ionizing lead it can create positive charge and to be attracted."
You are correct in that freshly mined lead can contain traces of some radioactive isotopes with relatively short half-lives.
This is important when the lead is to be used as shielding for sensitive experiments and "aged lead" can be valuable even to using some found in old shipwrecks.
This reference gives some of the details:
Chemistry StackExchange, Is lead radioactive?Cavendish did use lead balls and I've no idea whether the results could have been affected but they were within about 1% of the current accepted value.
Measurements and demonstrations of gravitation have been performed with many materials.
The long post referred to below gives examples of some demonstrations using materials from rocks, bowling balls, iron and lead but these gave no numerical result.
Flat Earth Debate / Re: GRAVITY PROOF « Message by rabinoz on August 27, 2018, 08:56:40 AM ».
There is more detail on the BIPM measurements in this
.pdf file:
The BIPM measurements of the Newtonian constant of gravitation, G by Terry Quinn, Clive Speake, Harold Parks, and Richard DavisThat experiment used cylindrical copper–tellurium test and source masses.
The cylindrical shape was chosen because though the calculations are more difficult it is far easier to machine a precise cylindrical shape than a spherical shape.
And the copper–tellurium alloy was chosen because of its free machining quantities though other experiments have used tungsten because of its very high density.