Yes. You’re right that the input resistor configuration doesn’t allow for best protection here.
I thought though that the existing external diodes were also higher stand-off than internal and so it would not be making anything worse.
I’m no expert but I think that main risk is during ESD transients where the situation is quite complex with the transient conditions being significantly different from what a simple stable low voltage analysis indicate. So for sustained low voltage overload the internal will be taking the current but the series resistance will be fairly effective in limiting energy. Obviously putting on medium voltages for sustained periods is not going to do the series resistor much good depending on its rating but that is a low risk when using these inputs for what they are intended. For high voltage pulse the external diodes may help redirect the energy depending on the transient behaviour of the internals and provide better protection