Hi Jan,
my tests with german special characters (ÄÖÜäöü?) tested with:
tcpdf_fonts_unzip_first.zip
Phoca PDF Component v6.1.0Beta3,
Phoca PDF Content Plugin v6.1.0,
Phoca PDF Phoca Cart Plugin v6.1.0
cid0cs (cid0) Ok - (Irregular spacing between characters) Ok - (Irregular spacing between characters)
cid0ct (cid0) Ok - (Irregular spacing between characters) Ok - (Irregular spacing between characters)
cid0jp (cid0) Ok - (Irregular spacing between characters) Ok - (Irregular spacing between characters)
cid0kr (cid0) Ok - (Irregular spacing between characters) Ok - (Irregular spacing between characters)
courier (core) Ok Ok
courierb (core) Ok Ok
courierbi (core) Ok Ok
courieri (core) Ok Ok
helvetica (core) Ok Ok
helveticab (core) Ok Ok
helveticabi (core) Ok Ok
helveticai (core) Ok Ok
symbol (core) Not Ok Not Ok
times (core) Ok Ok
timesb (core) Ok Ok
timesbi (core) Ok Ok
timesi (core) Ok Ok
zapfdingbats (core) Not Ok Not Ok
dejavumathtexgyre (dejavu) Ok Ok
dejavusans (dejavu) Ok Ok
dejavusansb (dejavu) Ok Ok
dejavusansbi (dejavu) Ok Ok
dejavusanscondensed (dejavu) Ok Ok
dejavusanscondensedb (dejavu) Ok Ok
dejavusanscondensedbi (dejavu) Ok Ok
dejavusanscondensedi (dejavu) Ok Ok
dejavusansextralight (dejavu) Ok Ok
dejavusansi (dejavu) Ok Ok
dejavusansmono (dejavu) Ok Ok
dejavusansmonob (dejavu) Ok Ok
dejavusansmonobi (dejavu) Ok Ok
dejavusansmonoi (dejavu) Ok Ok