[Maédhros]

Wrong. This is not the question. Many people think it is, which is why it has been so difficult for them to wrap their brain around Tolkien's very simple statement. Tolkien does not put conditions or limitations on Luthien's greatness.

No. You can´t be the best in everything. While she might be the greatest in certain things, she certainly isn´t the best artisan of the Eldar. I would give that to Feanor, who after all made the Silmarils.

In Eregion the craftsmen of the Gwaith-i-Mírdain, the People of the Jewel-smiths, surpassed in cunning all that have ever wrought, save only Fëanor himself; and indeed greatest in skill among them was Celebrimbor, son of Curufin, who was estranged from his father and remained in Nargothrond when Celegorm and Curufin were driven forth, as is told in the Quenta Silmarillion.

I don´t see any statement made by JRRT that supports that Luthien was better at crafts than Feanor. Neither in the creation of words.

We don't have any account of her applying herself to crafts.

So wouldn´t JRRT mention if she made something as great as the silmarils.

Feanors Silmarils were hallowed by Varda, or they would not have been as great as they were.

As three great Jewels they were in form. But not until the End, when Fëanor shall return who perished ere the Sun was made, and sits now in the Halls of Awaiting and comes no more among his kin; not until the Sun passes and the Moon falls, shall it be known of what substance they were made. Like the crystal of diamonds it appeared, and yet was more strong than adamant, so that no violence could mar it or break it within the Kingdom of Arda. Yet that crystal was to the Silmarils but as is the body to the Children of Ilúvatar: the house of its inner fire, that is within it and yet in all parts of it, and is its life. And the inner fire of the Silmarils Fëanor made of the blended light of the Trees of Valinor, which lives in them yet, though the Trees have long withered and shine no more. Therefore even in the darkness of the deepest treasury the Silmarils of their own radiance shone like the stars of Varda; and yet, as were they indeed living things, they rejoiced in light and received it and gaveit back in hues more marvellous than before.
All who dwelt in Aman were filled with wonder and delight at the work of Fëanor. And Varda hallowed the Silmarils, so that thereafter no mortal flesh, nor hands unclean, nor anything of evil will might touch them

Fëanor´s silmarils were hallowed by Varda because she was filled with wonder by the works of Fëanor. Her hallowing the Silmarils didn´t made them greater or more beautiful, it just made them "untochable" to evil hands. They were already the best work ever done by an eldar.