Was Peach's third letter in SMB3 really about the white fall-thru platforms?

In the original Super Mario Bros 3 game, the third Peach's letter reads:

Most players assume this to be a reference to the white platforms that allow the player to drop behind the scenery when the down/crouch button is kept pressed for a few seconds. This answer even goes as far as claiming that the mail is an hint for finding the hidden whistle hidden behind the scenery at the end of level 1-3.

Yet, apparently the original Japanese message reads:

しろいぶろっくは てきを けちらす まほうの ちからが あるそうよ

which based on multiple source and comments on this question roughly translate to

"White blocks" seems to have a magical power to kick/rout enemies

While both version do indeed mentions that the block can be used to "defeat/kick enemies" the translated Japanese version specifically looks like it would fit the "white block" that Buster Beetles throw at Mario in some levels and can also be used in the same way by the player. Because of that it would seem that it makes more sense for the letter to be about those throwable blocks instead since the fall-thru platform can't really be used to "defeat your enemies" like Peach suggests in her letter.

... Yet again the Mario Wiki seem to imply that those blocks are considered a type of Ice Blocks , never calling them anything close to "White Blocks". And at the same time the old Nes Game Atlas (should be official) does indeed use the name "White Block" for the white fall-thru platforms.

So... can anyone with a better understanding of Japanese find any confirmation about the original meaning of the message? Is this just another misstranlation that by pure chance ended up to fit another, actual gimmick in the game or was the message really about the white fall-thru platforms?