1) I'd like to ask about Ayatollah sistani's position in tatbir for Imam hussain if no serious harm is caused and it happens in private (so that it won't be seen by non-shias to be used as a source for mockery)

2) I'd also like to ask about his position regarding doing jaza(chest beating,crying loudly,etc) for masomeen other than Imam Hussain

3) Is chestbeating for any imam other than imam hussain haram?

1- S. Sistani is not giving any opinion about tatbeer, neither in public nor in private.
2- According to narrations, Jaza'a is only allowed for Imam Hussain
3- No