Unicode characters in quoted characters of Prolog text

Current draft TS: unicode.pdf

Test cases:

Tested with: 
?- set_prolog_flag(double_quotes, chars), read(Q), Q.

Input GNU Prolog 1.5.0 Scryer Prolog 0.9.4 SWI-Prolog 8.3.15 Trealla Prolog 2.23.3
char_code(C, 0x1f49c), writeq(C). r.e. 'πŸ’œ' πŸ’œ 'πŸ’œ'
writeq('ΓΆ'). 'ΓΆ' ΓΆ ΓΆ ΓΆ
length("ΓΆ",L),writeq(L). 2 1 1 1
writeq('α™œ'). — α™œ α™œ 'α™œ'
writeq('πŸ’œ'). — 'πŸ’œ' πŸ’œ 'πŸ’œ'
writeq("πŸ’œ"). — ['πŸ’œ'] [πŸ’œ] ['πŸ’œ']
writeq('𝔄'). — '𝔄' '𝔄' '𝔄'


Notes. 
00F6;LATIN SMALL LETTER O WITH DIAERESIS;Ll;0;L;006F 0308;;;;N;LATIN SMALL LETTER O DIAERESIS;;00D6;;00D6  buffer code: #xC3 #xB6
165C;CANADIAN SYLLABICS CARRIER TSO;Lo;0;L;;;;;N;;;;;                                                      buffer code: #xE1 #x99 #x9C
1D504;MATHEMATICAL FRAKTUR CAPITAL A;Lu;0;L;<font> 0041;;;;N;;;;;                                          buffer code: #xF0 #x9D #x94 #x84
1F49C;PURPLE HEART;So;0;ON;;;;;N;;;;;                                                                      buffer code: #xF0 #x9F #x92 #x9C