I know Simon 4 was here (Chaos Happens) but is it available anywhere? And Simon 5 (Who'd even want contact) is nowhere legally to be bought?

If anyone has any knowledge, please tell me. I love Simon the Sorcerer.

It doesn't sound good:

https://www.gog.com/forum/simon_the_sorcerer_series/simon_the_sorcerer_5

Looks like 4 used to be here but the rights (and therefore the game) got pulled:

https://www.gog.com/forum/general/simon_45

Do yourself a favor and ignore 3, 4 and 5.

Do yourself another favour and don't buy the "enhanced" versions.