Translation strings from install profile config language/[langcode]/*.yml files don't appear in locale_target

Problem/Motivation

When i create install profile for multilanguge site i need to provide default translated strings for different settings. In my case it is custom setting for custom search form block provided in custom module.
i put yml of the block into profile/config/install
my settingsis:
...
settings:
id: mymodule_search_block
label: 'My module search block'
provider: mymodule
label_display: '0'
form_type: global
text: ''
placeholder: 'Enter your search'

i also place translated string into profile/config/install/language/fr/ folder

settings:
label: 'My module search block'
placeholder: 'Saisir votre recherche'

also discribed schema yml file placed in mymodule/config/schema/ folder

block.settings.myblock:
type: block_settings
label: 'Search form block'
mapping:
placeholder:
type: label
label: 'Placeholder'

shema was checked with config_inspector module.
so placeholder is translatable setting of block config

but after install profile translated doesn't come into locale_target and then language config override disappear
after invoking http://cgit.drupalcode.org/drupal/tree/core/modules/locale/src/LocaleCon...
on the last install stage because it is translatable setting and because it is not present in locale.

So it looks like bug that it doesn't come to locale during installation.