The cluster networks "assume" operating mode based on frequency. They do not have sufficient "smarts" to differentiate between modes when the SPOTTER does not include the MODE in the comments.
IOW, the cluster software is brain dead - particularly for "JT mode" operations away from the "standard frequencies".
73,
... Joe, W4TV
The structure of a cluster spot, "^" delinted text, does not have facility for recording the mode, thus determining the mode is left to guessing based on frequency or by extracting from spot notes. eg. "18079.9^VK3AMA^1272029820^comment^AX3AMA^8^95^VK3AMA-2^41^21^45^25^^"