Is there a way to do this reliably ? I realized that on my first ever playtrough i had brilliant inspiration from watcher specific skills and then all the other times it was something else,any1 knows correct conversation choices to get it ?

It depends on the dialogue with Eothas etc. you do before getting those skills upgraded. I don't remember the exact options you have tp pick, but it is reproducable.  

Gods talk with you after port maje , hasongo and magrans teeth right ? I know i need to get intelect first time when i talk with them after port maje so i guess after that i could do everything i want to do before magrans teeth and then just go hasongo>magrans teeth and hard save before that to get multiple tries ,damn i hate annoying mechanics like that where getting brilliant vs any other inspiration is actually a huge deal

solution is there, dialogs may differ a little depends on backstory and party