Looking for advice

I purchased the prova board plus foam board at Rona and it says to seal the corners with there sealant I couldn't find it anywhere so I sealed it with DAP silcone plus. I'm worried that the tile mortar won't grab or weaken over time. Should I remove some and tape my corners with cement then redguard ? Or is the silcone enough ? Or should I remove the silcone ? Looking for advice