FSRS "evaluate" message has only partial i18n support

**How to reproduce:**

In the deck options, FSRS, click on the button "Evalute". You get a message dialog like that:


**Actual behaviour:**

The first part of the string "Log loss: 0.4109, RMSE(bins): 4,73%." is not internationalized: It does not show up in Pontoon for translation.

**Expected behaviour:**

All elements of the string show up in Pontoon for translation.

Start in the deck options FSRS flow at the “Evaluate” button and locate the message that formats the Log loss and RMSE values. Check how that message is exposed for translation in Pontoon; done means every part of the displayed string appears as translatable text.

Written by the indexing model from the issue text.