Did you charge the Rockcutter? If yes, then its just an updatebug. The Silktouch-III gets removed when the Rockcutter has less than 500EU and you get it back when it has more than 500EU. You dont need to know about the "Enchantment", it shouldn't be shown in the Tooltip at all.
The rock cutter is fully charged - 10000/10000 EU. I tried it with and without a batpack.
Wasted all the EU on cobblestone, then charged to 600 EU in a batbox, still not silk touch.
Put on a batpack (with 100EU in cutter) and the cutter doesn't use the energy from the batpack - a different bug?
Recharged to 900EU, broke a block, the cutter recharged from the batpack but still doesn't use silk touch.
I'm using smoothstone to test it, if it matters.