Reece H. Dunn
I don't know this area of espeak to say what it's cababilities are in this regard. As for espeak-ng, write up a proposal in the issues describing the requirements you have for your needs w.r.t. Italian so they are documented.
I think espeak is weighted toward English stress patterns.
Ideally, two things should happen:
1. Document the current stress behaviour in espeak;
2. Investigate the different stress, tone and intonation patterns found in different languages and annotations for those languages (e.g. IPA tone marks);
3. Design a framework that captures the requirements to support the things identified in (2);
4. Implement (3) in espeak-ng.
I am currently looking at the voice/language/accent split within espeak-ng, so don't have time right now to look into improving the stress/tone/intonation support, but if someone else wants to look into this they can do.