For the lamps' color at night I used Palette 12 (for the tilesets in A-Map's block editor) as the 'lit-up' colors. Normally that palette is not used to display things in-game, but one or two tilesets might still use it for some tiles. What I did first though, is to uncheck Palette 12 in the program Day Night & Seasons when implementing the day-night feature. This makes that palette unaffected by darkening/changing of the surrounding environment. This setting can still be changed after without re-inserting the feature, just be sure to apply/save the changes.
The way the light-up function works is to use a level-script (specifically for the "setmaptile" command). On maps that I wanted have the light-up function on, I set it up to where the 'setmaptile' script check's what time of day it is, and if it is dusk/night time, it changes specific tiles to another tile in the tileset. In this case, they are changed to a duplicate of themselves that have some colors changed; like to the color yellow/white on parts that are lit. Of course, you will have to find some unused tile squares in that tileset for the alternate ones, and unfortunately the unused space in Emerald's tilesets is rather limited. You could probably used A-Map 1.95 to insert a new, bigger tileset, and copy the hex data from the old one to the new one. However, you'll probably run into issues along the way because of the high probability of things not working like they should (tile animations and such).
Speaking of tile animations, that was the next step basically. I used "Tile Animation Editor" by Lu-Ho (creator of Advance Map), and tutorials like these:
-
https://www.pokecommunity.com/threads/305186
-
https://www.pokecommunity.com/threads/260619
-
https://www.pokecommunity.com/threads/260619
For tile animations you will need to have separate images for each part of the animation, designed in something like MS Paint, and with the same 16-color palette for each. Also keep in mind transparency and stuff to avoid the whole tile being lit up at once. To get new tiles into a tileset, you will also have to first save the tile blocks to your computer, edit them in Paint, etc., and then reinsert them with the new tiles (making sure not to edit the palette outside of A-Map's palette editor window). Tile blocks that have animations have to be arranged in a kind of side-by-side way for the game to use them properly.
I hope this helps!