I'm going to go ahead and make the following changes, but I wanted to give you a heads up for these:
The pattern for language keys is:
If it's a label (meaning, it's not a sentence, and shouldn't have a period at the end), then every word, except for articles, should be capitalized.
If it is a sentence, then it should follow normal capitalization rules, and it must have a period at the end.

For instance:
"Delete portlet data." and "Delete Portlet Data" are both correct, as the first is a sentence and the second is a label.

Below, you removed some periods, but didn't convert them to following the label rules. I'll add the period back. If these should be labels, then once it goes into core, I would send the changes over to Brian following the proper rules.