Because you're whining and overreacting about one particular thing that you dislike.
They are tagged "Japanese game" because they were made in, surprise surprise, Japan. Btw, there are 30 games per page, not 20. In the last 3 days a total of
93 games were updated only
11 games are Japanese Games. If you think that 11,82% is spamming then you clearly have a problem. Maybe you want to take a screenshot of those " 10 MTL threads in a row" to illustrate your point, because those 11 games in the last link I posted seem scattered.
If you want to know something about a game, you can ask in that game's thread. If your problem is that the game isn't tagged as "Japanase game" (if you have been here since 2019 and you still can't tell it's a japanese game just by looking at it then you have another problem) you can report it so it gets tagged properly. If your problem are MTL games, then avoid playing games MTLed, like Japenese games for example.
Sure, the forum could add a MTL tag, it could add a lot of tags to make things easier, but no matter how many tags F95 adds it still won't be clear enough for some players. You can request that tag in the right section of the forum, but as long as that tag doesn't exist, you'll have to deal with and find another solution.