The character attribution's Font Language edit field accepts valid BCP 47 language tags to be added, except x-... private-use tags, on purpose to prevent spreading misassignments. It should allow adding language tags for artificial constructed languages though with tags art-x-... and art-Latn-x-... (with Latn being any valid script code) so these could be used without the kludge of having to create and edit the stored source of a document (see https://ask.libreoffice.org/t/how-to-create-an-exportable-keyboard-input-scheme/80482/4 ) See also https://en.wikipedia.org/wiki/Codes_for_constructed_languages https://www.kreativekorp.com/clcr/
Eike Rathke committed a patch related to this issue. It has been pushed to "master": https://git.libreoffice.org/core/commit/2c2e0568e89942cc8463c0da9aa7a3d177667178 Related: tdf#150370 Convert isValidBcp47() bool to enum LanguageTag::PrivateUse It will be available in 7.5.0. The patch should be included in the daily builds available at https://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More information about daily builds can be found at: https://wiki.documentfoundation.org/Testing_Daily_Builds Affected users are encouraged to test the fix and report feedback.
Eike Rathke committed a patch related to this issue. It has been pushed to "master": https://git.libreoffice.org/core/commit/24d382a18ec2ade0d9e9b9c6e6c3e86bed6cde14 Resolves: tdf#150370 Accept 'art-x-...' private-use input in language box It will be available in 7.5.0. The patch should be included in the daily builds available at https://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More information about daily builds can be found at: https://wiki.documentfoundation.org/Testing_Daily_Builds Affected users are encouraged to test the fix and report feedback.
Fix verified: Version: 7.6.0.0.alpha0+ (X86_64) / LibreOffice Community Build ID: 01c9c971e43782800ebf63acc763a7e7fba096c1 CPU threads: 8; OS: Linux 5.15; UI render: default; VCL: gtk3 Locale: en-AU (en_AU.UTF-8); UI: en-US Calc: threaded