Hand2Note calculates stats accurately.

Problems are only possible with the calculation of results, especially for rooms that don't require auto-import settings.
For such rooms, there is no way to get accurate information about winnings, rake, etc. from the hand history file. Besides, Hand2Note may lose some hands while playing in such rooms due to the specificity of the process of gathering hands from these apps. Losses occur at random points in time, so it practically does not affect stats values on a big sample:

https://hand2note.com/Help/pages/Troubleshooting/Other/#loss-of-hands-in-asian-rooms