I've been checking this thread on and off, and what it all comes down to is that everything is open to interpretation. Whether or not Richard knew about Jason's parentage would depend on what Lois had known
from the very beginning.
Let's consider the following. If Lois didn't know of Jason's biological father, then that would make her a very stupid, clueless woman. (One could argue about the amnesia/memory loss, but that's assuming SR's continuity is linked to the first two Donner films). If Lois DID know who Jason's real father was and she kept it from Richard, that would make her a liar.
In sum, Superman/Clark didn't know (at least not at first).
Lois might have known.
Richard didn't know (IMHO, nor did he care) until it was made apparent to him.