Just some follow up before I answer:
Livy has this bit of reported speech (PHI):
Bacchanalia tota iam pridem Italia et nunc per urbem etiam multis locis esse, non fama solum accepisse uos sed crepitibus etiam ululatibusque nocturnis, qui personant tota urbe, certum habeo, ceterum quae ea res sit, ignorare: alios deorum aliquem cultum, alios concessum ludum et lasciuiam credere esse, et qualecumque sit, ad paucos pertinere.
-> Here the subjunctive follows most probably as a side effect of the reporting
. (when translated to Czech, the Czech
grammars do not doubt it's
NOT a subordinated clause, it's likely it's not a Czech thing only...)
The examples are scarce, but then there is one from Cicero, with indicative though (a counterexample):
hoc, qualecumque est, te scire volui.
-> but one could probably say that with "velle" one doesn't really "report" anything and that "velle" is just a "desiderative modifier" to the "main intended [lexical] verb (sciō, scīre)" and it just happens that the IndoEuropean syntax puts the main lexical(meaning carrying) verb to infinitive and the modifier to the finite tense (it may be different in different types of languages, right, as linguistics suggests).