Have a look at the style guidelines regarding ETI (Extra Title Information). Relevant details are included below (emphasis mine):
Additional information on a release or track name that is not part of its main title, but intended to distinguish it from different releases or tracks with the same main title (such as version/remix names or live recording info), should be entered in parentheses after the main title.
Titles and subtitles of mixes/versions are formatted according to the appropriate language’s guidelines; the other parts of this extra information should be in lower case except for words that would normally be capitalised in the language.
If your language requires the use of title caps or other non-standard capitalization rules (e.g. English), you may need to distinguish the title part and the descriptive part of the extra title information (ETI). If the ETI contains no names or title, keep to lower case. If it contains a distinct title, use the title capitalization rules. In case the ETI is a combination of title and descriptive parts, use lower case for the descriptive part only. The latter often contains words like mix, remix, live, remaster, edit, etc.
In the example you mentioned “reprise” is the descriptive part and “Tiberias’” is the title. I think you could reasonably argue that “theme” is also a descriptive part and so should be lowercase.
You can look at the javascript code that implements the guess case functionality to see which words are automatically lowercased:
/*
* Words which are turned to lowercase if in brackets, but
* are *not* put in brackets if they're found at the end of the sentence.
*/
const preBracketSingleWordsList = [
'acoustic',
'airplay',
'album',
'alternate',
'alternative',
'ambient',
'bonus',
'chillout',
'clean',
'club',
'composition',
'cut',
'dance',
'dialogue',
'dirty',
'disc',
'disco',
'dub',
'early',
'extended',
'feat',
'featuring',
'ft',
'instrumental',
'live',
'long',
'main',
'megamix',
'mix',
'original',
'piano',
'radio',
'rap',
'rehearsal',
'remixed',
'remode',
're‐mode',
'rework',
'reworked',
'session',
'short',
'take',
'takes',
'techno',
'trance',
'version',
'video',
'vocal',
'with',
'without',
];
/*
* Words which are turned to lowercase if in brackets, and
* put in brackets if they're found at the end of the sentence.
*/
const lowerCaseBracketWordsList = [
'a_cappella',
'clubmix',
'demo',
'edit',
'excerpt',
'interlude',
'intro',
'karaoke',
'maxi',
'mono',
'orchestral',
'outro',
'outtake',
'outtakes',
'quadraphonic',
'reedit',
'reinterpreted',
'remake',
'remix',
'rmx',
'reprise',
'single',
'skit',
'stereo',
'studio',
'unplugged',
'vs',
]