Opening up a .2da file requires a simple text editor, which Windows does support.
Start - All Programs - Accessories - Notepad.
By loading up the file in this text editor, you'll be able to see and review the required 2da files.
Conflicts with placeables are generally found when a numbered line in one 2da file has been replaced by another from a second 2da file. As we're dealing with placeables which come from Bioware, one of the placeable haks you're using - or a hak in general that has a placeables.2da in it - is most likely old and not updated to 1.69.
The Barrow Pillars, from the stock 1.69 placeables.2da file can be found on line number 814 to 817. The second placeables.2da that is causing the conflict will most likely have something else at this number, which is making the barrow pillars become something else.
Padding a 2da file should be done by using the stock 1.69 placeables.2da file, so you know you're working with the most recent 2da update. This is the file you'll want to add new placeables to each time you download a new hak and it has a placeables.2da inside.
It's best you make your own hak anyhow when you start merging content together as it will be a requirement for much of the haks that add new content, such as placeables, armor, sound, item appearances, etc.
Anyhow, any new additions need to be added at the end of the placeables.2da file and numbered accordingly.
So, if this new hak you added has a placeables.2da file, you open it and find the content you want to add, searching the placeables.2da lines for those placeables. Highlight the entire line and copy it to the placeables.2da you'll be using in your own hak. Append this copied line to the bottom of the new placeables.2da file. Renumber.
So if I was going to add 50 new tree placeables, I'd open up the tree placeables.2da, find all the entries for the 50 trees and copy these lines to my own placeables.2da. Using this as a reference, the last entry for a 1.69 placeables.2da file is:
846 GygaxStatue 5734 PLC_S10 **** **** **** **** 17 1 0 **** dlag__ref01 1
So those 50 placeable tree entries would start at line 857 for one tree, 858 for the second tree, all the way up to 896 for all 50 trees.
FP!