Silken tofu also comes in different types like regular tofu, like firm, medium and soft, but can be used interchangeably without affecting the texture of the dish, mostly because whatever the type it may be, it is generally blended along with the other ingredients in the recipe. So it should not be a problem as to what type of silken tofu you choose to use.
These days silken tofu or any tofu for that matter is readily available in most grocery stores whether Western or Eastern. You can look for it in the refrigerator section along with cheese products in some stores, or natural/organic section. The ones in aseptic boxes doesn’t require refrigeration. So just ask the store clerk if you have problem locating it or you can buy online here.