Light plays a big role in what you think you see. In your example the light is coming from the left so there is shadow in the space between the pip and the triangle edge on the right. It could easily look centered if it was shown with a dead center light source.
For ones that actually are off center, it's best to either live with it and get over it or just replace the insert. It's far too much risk and expense to try to correct it. I have reattached pips to ceramic inserts when it was needed but to pull one off and move it a slight amount is a crazy notion.
Sometimes there is no room to move it in the direction needed because of the pearl cup shaft butting up against the hole in the ceramic. I've grinded that shaft off once to do a pip replacement on an insert in place but wouldn't go to those lengths for a tiny visual improvement.