IANAL but according to the Creative Commons Foundation although the CC-BY-SA 3.0 license allows you to license your new contributions under a CC-BY-SA 4.0 license it doesn't allow you to "upgrade" the original CC-BY-SA 3.0 license of the original work. So technically the effective overall license of your translated work will be a CC-BY-SA 3.0 + CC-BY-SA 4.0 "license stack" (i.e. downstream users must technically comply with the terms of both CC-BY-SA licenses and not simply just the CC-BY-SA 4.0 license). Such a license "upgrade" mechanism was newly introduced with the CC-BY-SA 4.0 license but doesn't retroactively apply to the CC-BY-SA 3.0 license.
Relevant quotes from Creative Commons:
In version 4.0, CC added a provision in the ShareAlike licenses that enables downstream licensees to refer only to the adapter’s license when using adapted material that contains the copyrightable contributions of multiple authors. This feature is designed to minimize complexity for reusers where they are using a later version of the ShareAlike license or a compatible license as their adapter's license. In 4.0, users need only refer to a single set of conditions contained in the last license applied to reuse adapted material, rather than parsing the conditions of the original and other adapter's licenses (to the extent the licenses differ).
In all cases, the licenses stack (the later license does not supplant all previously-applied licenses) when adapted material is created. In particular, the license originally applied to the material being remixed continues to apply once remixed, however permission is given in 4.0 for licensees to meet the conditions of the 4.0 license with reference to those in the adapter's license.
Prior to the 4.0 versioning process, CC had not always been clear that the ShareAlike licenses stacked just as they stack for the BY and BY-NC licenses, and reasonable minds do differ on this point. CC believes, however, that this is the best reading of its all of its licenses that permit adaptations prior to 4.0 and, now, has made that explicit in version 4.0.