Update:
It seems like I finally started to get some luck, just got a second shiny! And with suprisingly good IVs
Shiny Riolu - 5IV (31/30/31/31/31/31)
After 446 riolu eggs (2336 in total)
Sadly, the little boy has Steadyfast instead of Prankster. But hey, shiny Riolu, I can't really complain...