There's so many terms and the semantics can make one crazy trying to figure it out. 

To put it very simply, insertion loss for a PIC is defined as the sum of the coupling loss, waveguide propogation loss, and material absorption loss. 

.25db for coupling loss is excellent. 

LioniX, a competitor to Ligentec, has advertised coupling losses as low as .3db. I imagine Ligentec is the same, if not better. 

Ligentec is a powerhouse in the SiN world. I heard the founders and its very few investors are making a fortune.