Both the "Hibernate Tools" and "Seam Tools" for JBT v3.1.1 have too narrow version requirements for com.ibm.icu to be compatible with Helios.

Helios comes with com.ibm.icu v4.2.1

Currently the version requirements are set to [3.4.4,4.1.0) so this should be changed at a minimum to [3.4.4,4.3.0) to allow both these JBT components to install on top of Helios.

However you should consider using an even wider version width of [3.4.4,5) since it is accepted practise that minor version increments are backwardly compatible and a major version change is potentially API breaking. This means that generally JBT should (and is expected to) work on all future versions of com.ibm.icu up until version 5 is released.