I’m skeptical. Their website says 900V, but their datasheet states otherwise, and looking at the part numbering of some of the others in this series, it seems to me like this is more likely just the 24V coil version of the B88269X1060C011, which is rated for 450V. Based on the part numbering, I think that the B88269X1090C011 is the first part number in the series rated for 900V.
Could they be confusing it with the B88269X2390C011? Both are called the “HVC200A-24S Type”, but this one is rated for 1000V.
I take it back. I now think they have failed to update the datasheet. Looking at the datasheet of the B88269X1000C011, which appears to have been updated, they added a service life test at 900V, shown in the graph on page 4 of the respective datasheet. The life is significantly reduced at 900V for a given current, but it shows that it can handle 900V at a reduced current level.