Relativity of verbs in subordinate clauses

Question

Verbs in subordinate clauses are "conjugated" relatively to the parent clause.

"Li pensis (past) ke si ludas (present, relative to parent clause) bonan muzikon"

But then what if there are nested clause pairs like this?

"Li pensis (past) ke si ludas (present, relative to parent clause) bonan muzikon, sed ĝi resonis tiel ke ĉiuj plantoj ĉirkaŭe forvelkas" (some commas omitted for clarity in separating the two bigger clauses)

This is like ((clause, subordinate), (clause, subordinate)), in a dumbed down syntax tree sense. Is the "resoni" still supposed to be in past tense (absolute, because the root level is in the present), or present tense (relative to the "pensi" in the first big clause)?

Answer 1

There are two main clauses here, "li pensis" and "ĝi resonis", that are made parallel, equal-valued (sorry, I know the term neither in English nor in Esperanto) by the word sed. At least to me the example appears like, that the actions in the main clauses are taking place at the same time, thus I would choose resonis.