How make recipe using a custom liquid bucket?

I don't think that is possible, sorry

might this get added?

a solution would be to make a bucket item with the top filled with the fluid you intended to use

I'll write procedure for working fluid bucket.

Trigger: Right clicked on block

Set block at x y z (or maybe better x y+1 z) to [custom fluid]

[If: get item from {event/target entity} {mainhand} = {custom fluid bucket}

Do: set item in {event/target entity} {mainhand} = {bucket}

Else if: 

get item from {event/target entity} {offhand} = {custom fluid bucket}

Do: set item in {event/target entity} {offhand} = {bucket}]

I think this can help somebody :)

the bucket is automatically created by forge/fabric in the misc tab (like water/lava), so you can't find that in MCreator, srry. :-)

I found solution

this is a code:

{
  "group": "[your group]",
  "type": "minecraft:smelting",
  "experience": [experience],
  "cookingtime": [coking time],
  "ingredient": {
    "item": "[your ingredient]"
  },
  "result": {
    "item": "[your group]:[name of your liquid]_bucket"
  }
}

how to use that code?