Beaglebone analog input naming question...

I know that implementation of a lot of stuff is forthcoming, but
following the hint given by Koen on his blog:

reading them seems to be somewhat possible. However, this has AIN1 -
AIN8. As far as I can tell, AIN1 corresponds with AIN0 on header P9,
with the other inputs incremented accordingly.

Is there some reason they have a different numbering than in the SRM?
Also, what does AIN8 actually correspond to?

The numbering on the schematic is AIN0-7. The numbering in the SRM is AIN0-7. P9 starts at AIN0 and goes to AIN6. That is the correct numbering as it also aligns with the processor datasheet. As to why Koen has it numbered from 1, you will need to ask him.

AIN7 input is connected to the TPS65217 and is not accessible from the expansion header. You can find information on that in Figure 14 of the SRM.