The internationalization module provides a method for synchronizing fields between various translations. This is a wonderful feature, but user experience is horrible.
When creating a new translation for a master node, the translator is presented with all fields on the node, and not just the ones he/she needs to translate. In my opinion this is confusing.
To resolve this, I've created a small helper module, which hides fields which are being synchronized when translating a node.
Unfortunately due to bugs in D6 CCK and D7 Fields relating to #access = FALSE, not all field widgets will be able to handle the method of "hiding fields" properly and this may cause validation errors when attempting to submit a node with hidden fields. To avoid this in D6, I've simply hidden the fields with CSS instead of #access = FALSE.
Below is a list of related issues I've found regarding this bug. Should you find more, please make it known in my issue queue and I'll keep the list up to date.
I would recommend, in order to resolve this problem, that simpletests are written which test with the inclusion of #access = FALSE with regards to field widgets. Hopefully this would catch the bugs and allow developers to resolve them, so modules like mine would work.
#1114402: Support for FAPI #access=FALSE
Some more reading on #value vs. value with regards to D6 CCK fields.