Transex3: modify src list localization/merge part

Avoid using numbers to identify the list items because
using numbers can lead to mixed translations. Use the
corresponding string instead.

Remove a hacky solution for mixed translations.
See: 95ea6cb21a7d7f4f163e642ba4b1e165a427a0d1

Change-Id: I6f1d48bf71fe2146f04f53c6b474dd7c0ce98678
Typo fixes in Math tooltips

Change-Id: I7623fd53dd60fdfd9afb99135b79adfb434aa72a