Once the uniquely shaped clockwork guns appeared, players understood one thing: Flintlocks are not invincible.
Only things that go beyond the developer's designs could possibly be invincible.
The emergence of the clockwork guns confirmed that firearms were indeed a part of the developers' design. Their appearance just happened so late, that everyone mistakenly thought that the players developed thermal weapons were "cheating weapons" – of course, Cloud Dream's achievements were quite misleading...
Since these are things that were originally a part of the game, they certainly can't be invincible.
The challenges that Shuihua and Victoria later faced could be used to validate this.
For the first six rounds, the effects of the flintlock were astounding, striking major blows to the opponent with each successful shot, leading them to victory.