Hello!
Thank you for your feedback.
TLDR: you can simply replace the card art you want by placing the card art in the YGO_Omega\Files\arts with the #######.jpg with the numbers being the card ID of the card, located in the bottom left hand corner of the card.
The TCG has created card art to “censor" the original art for the game from the OCG. The late Kazuki Takahashi, creator of the game, famously had a strong stance against his art being censored. This is the exact reason why the card Magi Magi Girl has not be introduced into the TCG as it would REQUIRE censorship based on the TCGs stance on card art reducing the “child-friendly” design.
Due to this, the Omega team views that the game is intended to be played with the Uncensored art, as that was the first release of the art. While there are some exceptions on topics that are generally unaccepted in places, the general stance is to support the game’s original intent, rather than a westernization view of the game. This is an international game, with the origination of the cards Japan.
On the technical side, maintaining multiple arts is actually more difficult that it seems. In order to provide a secondary card art, an entirely new card must be made. This separate card requires its own card art, naming, card script, and card is entry into the card database. This can cause issues with cards that interact with cards, cards which have their effects changed, or are searched by name (card is). When something changes on the original, it is a manual process to go back and apply those changes to the copy, a process we do not have the consistent access to.
Because of this duplicates are an exception made for normal monsters, cards which are old, or extremely unique circumstances. They go against the original wishes of the creator of the game. It’s extra burden technically for the team and are something the user can change themselves if they wish through the method outlined in the TLDR.
If you have any questions, please feel free to ask. Thank you for helping to make YGO Omega the best it can be.