The Japanese launcher download page (https://www.minecraft.net/ja-jp/download ), specifically the one for Windows 10/11, should be ランチャー (launcher), but it is ドランチャー (dlauncher).
Perhaps it was copied from the Mac version of the string, which is ダウンロードランチャー (Downloadlauncher)
Fix:
This appears to have been corrected. 🙂