I have a factory image from the pak192.comic I repainted. The original is from Leartin. I hope he doesn't mind 
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Not as long as you honor the license in case you publish it.
BackImage[A][B][C][D][E]=Filename without extension.row in Image file.column in Image fileWhat? 
It's really not the best rendition, confused me a bit as well. Maybe a bit clearer if everything that needs to be substituted is in brackets.
"BackImage[<A>][<B>][<C>][<D>][<E>][<F>]=<path/name>.<r>.<c>,<x>,<y>"
Substitute the following:
<A> : The rotation of the building
<B> : "Row" of the building tiles (considering top-right edge to be the top)
<C> : "Column" of the building tiles (considering top-right edge to be the top)
<D> : Height level (Usually only used on first row/column)
<E> : Animation step
<F> : Season (buildings can have 1 (always summer), 2 (summer, snowy), or 5 (summer, fall, winter, spring, snowy) seasons)
<path/name> : the image file and it's path relative to the .dat-file, but without file extension (.png) - eg. if the image is in a subfolder "images", and called "my_image.png", you'd write "./images/my_image". If makeobj can't find the image, more often than not it's the path that's wrong, at least in my experience.
<r> : Row the specific graphic is in the image file (start counting at 0)
<c> : Column the specific graphic is in the image file (start counting at 0)
<x> : Offset on the x axis the graphic is displayed at in the game (can be negative)
<y> : Offset on the y axis the graphic is displayed at in the game (can be negative)
There are a lot of parameters, and it gets even more complicated with shorthand dats (instead of writing one line for each image, it can be compressed into one line, as you probably saw in my money printer).
On the one hand, it would be easier to learn by ommitting most of them, reducing it to "BackImage[<A>][<B>][<C>]=<path/name>.<r>.<c>" - but on the other hand, that would cause even more confusion if someone looked at existing datfiles and wouldn't have a reference for what all of it is.
As Vladki mentioned, FrontImage is intended for objects that share a tile with vehicles to tell the game what's in front of the vehicle. Think of Depot roofs. For regular buildings, next to animations, it can also be used with an offset to have parts of a building hang into the next tile (eg. a wide treetop), or to get more out of lightcolors (the lightbulb you removed is an example of that - in the backimage, it's just the color that glows at night, and the Frontimage adds some semitransparent details to it). Not exactly a topic you need to know much for starting out, and it wasn't really intended for FrontImage to be used like that in the first place.
Because a game like Simutrans would not exist without it's creators and still needs them for it's own survival I think that it is critical that this is addressed. At least if you plan for survival beyhond your own interests.
If you adress it, you'll quickly find yourself in a blame game of where to document, how, and who should do it. The only agreement easily reached is that yes, indeed, there should be more documentation (and more translation). At this point, personally, I'd say just ask whatever you want to know and can't find easily using words that the next person would probably use to search for the same question.
Oh yeah... I can't access my regular PC at the moment, but I should still have Photoshop files for that building. With a bit of luck, changing colors could be as simple as applying an effect to a layer/group that contains the element. With less luck, at least the shadows are on a seperate layer, such that colors can be adjusted underneath it.
