Very interesting - does the account give a view of how big the Spanish party was to start with? If they have suffered 50-60 fatalities I assume fairly large.
And if the Maya can largely surround the Spanish then their force must be considerably larger.
The Maya seem to produce a huge volume of light missile fire, which is causing more wounds than kills, it seems. Presumably the Spanish musketrery is lower volume but more deadly.
Overall it feels a classic asymmetric fight with very different levels of technology on each side, but also with a good amount of morale coming into play?