Fair warning: Translations in Salesforce are painful. This is the least bad option I could find and I spent 4 hours working on this in May 2020. -InfoCynic
Please avoid putting special characters or commas into the API names of picklist values. If you make a picklist value that has special characters, please edit it afterward to change the API name to something safer. This will greatly reduce the time it takes to make working translation files.
Microsoft Excel Any text editor capable of changing the file encoding; e.g. Notepad++