This quote from the notes. "Losing the post after Stilicho's murder in 408, he was joined by Greuthingi, by ex-prisoners from the army of Radagaisus and by escaped slaves, and plundered Rome" suggest that his cavalry numbers should have increased at this time. However, in the army lists, the following "Allied Greuthingi and Alans under Alatheus and Saphrax (only in 378 CE)" suggest that this cannot happen. Is the date restriction (378AD) only relating to the Alans? thanks.
No the 378 CE date restriction applies to all the cavalry in that section.
I am not sure that the note about additions to Alaric's army is entirely accurate, specifically the mention of Greuthungi - however, I'd have to check. But it may indicate that a few extra cavalry may be appropriate - but the list note on supplies is important and correct so it wouldn't be many.
Thanks. Perhaps another unit of so of Cavalry but not the large numbers as suggested by the Greuthing or Radagaisus parts of the list.