I find this species rather intriguing because I have found it comes in three quite distinct colours in this area.
The red version looks very similar to H.rubrocarnosa, and unless one looks at the spores it is almost impossible to tell them apart. H. firma has dimorphous spores ie. the spores come in two distinct sizes. It is the only member of the Hygrophoraceae family with this feature.
The yellow version comes up yellow - they are not faded red ones. Likewise, the orange comes up orange and remains orange.
H. firma is also found in SE Asia, where at least 17 varieties have been found.
This image shows the dimorphous spores - two distinctly different sizes - that H. firma produces.