Defining translations for nested forms in namespaced resources

I have the below setup

class BudgetLine < ApplicationRecord  has_many :budget_line_items  accepts_nested_attributes_for :budget_line_itemsendclass BudgetLine::Accommodation < BudgetLineendclass BudgetLineItem < ApplicationRecord  belongs_to :budget_lineend

Now I'm trying to specify labels for the nested form of BudgetLineItem inside BudgetLine. According to the i18n documentation, you can normally do something like this:

en:  activerecord:    attributes:      user/role:        admin: "Admin"        contributor: "Contributor"

This works if the model in question is not namespaced, as with User above. However, when you want to specify a namespaced model it has the same syntax, so it becomes:

en:  activerecord:    attributes:      budget_line/accommodation/budget_line_items:        unit: Room

which does not work.

I've tried different variations of this, e.g.

en:  activerecord:    attributes:      budget_line:        accommodation/budget_line_items:          price: Price (USD)

which also does not work, because this way of specifying namespaces in locales seems to be deprecated.

As far as I understand, for the label to be translated correctly, the following should return the correct translation: BudgetLine::Accommodation.human_attribute_name("budget_line_items.unit"), but so far I've been unsuccessful in my attempts to target this.

Is there a way to solve for this use case?