For the Bangla version of a problem statement, it is not possible to put alternate text (Bangla) in Note section of sample test case.
The text there is written in the path:
Draft problem -> Edit -> Tests -> Create/pen a test -> Note
It shows up in the problem statement in the red marked part of the following screenshot.
As the English text is forced there, it appears quite odd in a statement where the rest is in Bangla.