Worth assessing. Does the leakage relate to heavy rains?
I have had over the years two clients whom related leakage around windows inside the house . The cause was traced back to lack of drip edges on the roof, so in heavy rains, the gutters overflowed, , got beind the facia aluminum and that was compounded by the soffit being sloped back towards the house, so the overfloww would flow down the soffit to the wall(which with simple application of a level showed it was sloped towards house!), and underneath sheeting/siding until it hit the widow sash, where some of it just got diverted into the wall and into the interior
1st client was a bit of a **** show, as they had just had seperate contracors redoing roof, another did insulating siding, and another sub installing gutters. Never did find out the outcome, but I id'd the cause. Everybody pointing fingers at each other
Client#2 got all new windows/.....30k$+, when all they had to do was get drip edge installed (and have their gutters cleaned!)
And in Calgary area I've seen many stuccoed houses installed without drip caps over the window/door openings. In that case, water sheeting down the sid eof the wall hits the door jamb/window trip,and a bunch of it goes inside.
Sometimes there's a simple cause! All of those causes are easily checked as well!