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 1.5.01 Scryer Prolog 0.9.4 SWI-Prolog 8.3.15 Trealla Prolog 2.23.3 Flowlog 4.9.6
1 char_code(C, 0x1f49c), writeq(C). r.e. 'πŸ’œ' πŸ’œ 'πŸ’œ' 'πŸ’œ'
2 writeq('ΓΆ'). 'ΓΆ' ΓΆ ΓΆ ΓΆ 'ΓΆ'
3 length("ΓΆ",L),writeq(L). 2 1 1 1 1
4 writeq('ΓΈ'). '\xc3\\xb8\' ΓΈ ΓΈ ΓΈ 'ΓΈ'
5 writeq('α™œ'). '\xe1\\x99\\x9c\' α™œ α™œ 'α™œ' 'α™œ'
6 writeq('πŸ’œ'). '\xf0\\x9f\\x92\\x9c\' 'πŸ’œ' πŸ’œ 'πŸ’œ' 'πŸ’œ'
7 writeq("πŸ’œ"). ['\xf0\','\x9f\','\x92\','\x9c\'] ['πŸ’œ'] [πŸ’œ] ['πŸ’œ'] ['πŸ’œ']
8 writeq('𝔄'). '\xf0\\x9d\\x94\\x84\' '𝔄' '𝔄' '𝔄' '𝔄'

  conforming
  extension
  wrong

1 Tested with: $ gprolog --init-goal "set_prolog_flag(double_quotes, chars)" --init-goal ShellquotedInput --init-goal halt

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