I'm trying to translate with a variable placeholder and it's working fine, except when the translation string begins with the placeholder.
E.g.
example.translation: %variable% example translation
If there is any non white space character before the first %, it's ok. Else it says the yaml file is invalid.
Although the percent sign probably could be allowed a the start of plain scalars that are not starting at the beginning of a document (where they indicate a directive), not all parsers allow this. You can check that online by comparing the Nim based parser with the PyYAML based one. The YAML specification explicitly disallows % (which is a c-indicator) from appearing at the beginning of a plain scalar.
You would run into similar problems if your edit would introduce colons (followed by whitespace) or backslashes.
The simple solution is quoting that value:
example.translation: '%variable% example translation'
I use single quotes here, as within those only single quotes have special meaning (if your original has a single quote, make that two single quotes).
Quoting YAML scalars with double quotes is also possible, but then any backlashes (\) and double quotes in the original must be preceded by a backslash (i.e. \\ and \")
You can also make such a plain scalar into a literal style block-scalar:
example.translation: |-
%variable% example translation
You'll have to use the - chomping indicator, otherwise your scalar ends in a newline, where the original did not. Then you don't have to
do anything special for single or double quotes in your original, nor for any backslashes.