[espeak-ng:master] New Comment on Issue #410 consecutive SSML tags aren't processed
By jaacoppi:

https://github.com/espeak-ng/espeak-ng/blob/0cb4b1b6542666919ae8b177f7bdb045e84e55ab/src/libespeak-ng/ssml.c#L704-L705 adding a return CLAUSE_NONE; here seems to solve the problem, but create others because the sentence end is not an intended consequence.

Something is done during the sentence end that causes the values for speech_parameters or param_stack to be read. Currently they seem to be set but not read.