Is there any way of editing the text of words in the interface?
The English has spelling mistakes that I'd like to fix, as it's quite annoying as it is. I used to use another Windows Explorer replacement and I edited a file to fix that one, so I'd like to have correct English again.
No, but if you report mistakes to us we will fix them, and then they are fixed for everyone else as well.
(Text on Toolbars can be edited, but not most strings. We'd still like to know about any mistakes.)
Either Americans would have to put up with words being spelt correctly for a change, or we'd need two versions of English.
Spelling mistakes below. I've put the mistakes in brackets after each line of text. I stopped after the first part of the preferences (the Display section). If this is going to happen, then I'll continue, if not, I'll stop now. Hopefully you can just do a few find and replace commands with a handful of words, save as a new language file, and it will be done.
Menus
Tools | Synchronize (Synchronise)
Tooltip: Show or hide the Lister Synchronize Panel (Synchronise)
Tools | Set as Desktop Wallpaper | Center (Centre)
Settings | Customize Toolbars... (Customise)
Tooltip: Lets you customize the toolbars and menus (customise)
Folder Tree
Favorites (Favourites)
Preferences window
Display
Colors and Fonts (Colours)
File and Folder Colors (Colours)
Files and folders
Colors for selected items are overridden (Colours)
Files and folders - Compatibility
Colors for selected items are overridden (Colours)
Files and folders - Compressed
Colors for selected items are overridden (Colours)
Files and folders - Encrypted
Colors for selected items are overridden (Colours)
Files and folders - System
Colors for selected items are overridden (Colours)
Folders - Favorites (Favourites)
Favourite folders (Favourite)
Colors for selected items are overridden (Colours)
Synchronize conflicts (Synchronise)
Synchronize conflicts (Synchronise)
Colors for selected items are overridden (Colours)
Other colors (colours)
Folder tabs
Use system colors (colours)
Folder tree
Use system colors (colours)
Colors for selected items are overridden (Colours)
Folder tree (destination)
Enable this color (colour)
Colors for selected items are overridden (Colours)
Metadata pane
Use system colors (colours)
Pane borders
Use system colors (colours)
Standard toolbar
Use system colors (colours)
Status bar
Use system colors (colours)
Fields
Custom color and font settings enabled (colour)
Text color (Colour)
Note: one of the fields is called 'Color space' (Colour)
Language
English
Note: This is obviously the problem. It calls it English, but it's actually American English. We need this splitting, into American English, and English.
Options
Blend file background colors with background (colours)
Blend row and column background colors (colours)
Blend selected items with column colors (colours)
Fade selected item colors when file display does not have focus (colours)
Fade selected item colors when tree does not have focus (colours)
Use visual style to draw items (overrides selection colors) (colours)
So we're not talking about spelling mistakes, but US vs UK spelling variations?
We could have a UK English 'translation' (I am in the UK myself), as Microsoft introduced quite recently for Windows itself, but it has never seemed worth the trouble of maintaining such a thing.
Well, a lot of us would consider them spelling mistakes. And it wouldn't be a translation, it would be correct.
It all depends on how much you care about your own language. I care a lot about mine, and would ALWAYS have English (or British English if you are American) as the default.
There are probably only about 5 or 10 different spellings. so a find and replace would take a few minutes. If you can be bothered to do 19 other completely different languages, doing English isn't such a big deal.
As George Bernard Shaw (purportedly) observed: "England and America are two countries divided by a common language".
Whether you/we like it or not American English is ubiquitous, even in the old colonies. If a British English language option was available in Preferences I would use it and I expect it would be a popular choice in the UK, Australia, India, South Africa, New Zealand, etc..
Regards, AB
Actually.
Actually it's not American or British English that is used. The language is Australian English.
Strewth! 
How did I miss that!
Regards, AB
If the Net is to be believed I reckon it must be Queensland English then.... 
http://www.onlinegrammar.com.au/us-and-australian-spelling/
http://grammarist.com/spelling/color-colour/
However, the icon on the Preferences language tab is admirably ambiguous about its preference:
Regards, AB
Never believe what you read!
We're just doing our bit to bring the anglophone world together 
It may seem like nitpicking to care whether an 'e' comes before an 'r' or not, for example, but I too care about my language, it being British English. Whenever a software provides English (United Kingdom) as a language option, I choose it. In a world where English is understood and written by many who have learned it as their second language, these differences aren't often understood or even realised. English is English. An easy mistake. To this day I am still discovering and trying to unlearn some American English habits. There are many software dictionaries used to display UK English so I'm not sure where the maintenance cost occurs (as mentioned in this topic) if one of those were utilised. Maybe I'm wrong.
(Apologies for the eight-year-old bump, but this looks to be the most relevant topic to add to.)