I didn't make the rpg60 engine and at the time I didn't really have much skills, the code i wrote was scripting code to program the game but I think it was made in C.
At the time I spent some time working with other italian guys on maintaining a small community around the tool but not much is left.
EDIT: now that I think about it I might actually still have it in some old HDD but it's in another country so you are unlikely to see it. What i did find is some screenshots from a Japanese web page! http://s60gamers.seesaa.net/article/17133227.html
Digging around leads to very few results, even archive.org struggles. I found a couple links tho but nothing you can download. https://web.archive.org/web/20071004112659/http://rpgrpg8.fr...
At the time I spent some time working with other italian guys on maintaining a small community around the tool but not much is left.
EDIT: now that I think about it I might actually still have it in some old HDD but it's in another country so you are unlikely to see it. What i did find is some screenshots from a Japanese web page! http://s60gamers.seesaa.net/article/17133227.html