Foreign tourists observed the nepali sculpture interestingly. why?

it is because Nepalese sculptors work in many media, including stone, metal, wood, and terracotta. Their metal sculptures are either heavily gilded or, if the gold has worn off, have a slightly reddish patina that derives from their high copper content. Many of these, especially later ones, are decorated with inlaid semi-precious stones. Wooden sculptures were generally architectural, many serving as struts to support roofs, as door surrounds, or as decorations. Works in terracotta are comparatively rare.

It was because of their religious significance

Explanation:

The Nepali sculpture were made of mainly bronze and copper alloys. The sculptures had drawings which represented religious backgrounds of Buddhism and Hinduism which was their main religions the country had affiliations with. These structures made the Nepali sculpture to be observed interestingly by tourists which was mainly due to their religious significance.