examples generate files where all items have name "Custom Item"
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from example:
<factory:item> .typed<Basic>() .tab(examplesTab) .rarity(<constant:minecraft:item/rarity:uncommon>) .build("very_basic_item");
so, how change name form "Custom Item"?

You'll need to add a lang file via a resourcepack. Folder structure for the Lang file would be as followed,

assets - contenttweaker - lang - en_us.json
Then within that file to name for instance very_basic_item, you would use

"item.contenttweaker.very_basic_item": "This is now named"
As for a block you would use
"block.contenttweaker.custom_block": instead of item and for creative tabs it would be "ItemGroup.examplesTab":