This is something our guild has started tracking in a separate Google sheet but it would be awesome to have within the addon. The idea is that when a new phase starts, the values reset and attendance is counted per raid day. Additionally, any loot marked as "Upgrade" or "BiS" counts as one piece of loot rewarded. So someone that has raided 3 days and gotten 2 pieces of loot would have a score of .67 while another raider that has raided 5 days and received 1 piece of loot would have a score of .2. The idea is to help "spread the love" to those who haven't gotten as much loot as others in the raid.

Some additional ideas:
Attendance would be by raid window and not day. So if a raid runs over midnight, it would not count as 2 attendance points.
Attendance and loot history could be shared/synced among raid members. This could get tricky but would be awesome if we could do it.

We're still a bit new to RC loot council so let me know if there are other features that could be used in place of what I mentioned here. If anything, perhaps something focusing on attendance alone would be better as far as implementing in phases. Also, thanks for your hard work on this great loot app. It's helped us out a lot in our loot council needs.

Attendance tracking is basically a whole addon's work in and of itself (several already exists).
It's something I want to do eventually (in fact already started working on), but it's a massive task (so far I'm at 3k lines of code, and that's without a UI), and I've put it on hold indefinitely. Maybe one day when I have time I'll pick it up again.

Most of the info you need is already available in the "More Info" tooltip in the voting frame though, albeit in a more basic form than full blown attendance tracking.

TSV (google sheets & english excel) Exports are old header format. I can't import something I export without modifying the header fields and columns manually in sheets every time. I also tried fixing it by exporting, deleting history, and importing with the new header field (such as boss, mapID etc). But when I export it's always in the old header format that doesn't support importing again directly without modification.

TSV (google sheets & english excel) Exports are old header format. I can't import something I export without modifying the header fields and columns manually in sheets every time. I also tried fixing it by exporting, deleting history, and importing with the new header field (such as boss, mapID etc). But when I export it's always in the old header format that doesn't support importing again directly without modification.

Uhm no. TSV is just not a supported import.

Tested

Turns out your wrong about TSV import, but I did have to read the wiki more carefully.
What I think you meant to say is that TSV Export is unsupported, as it's header fields aren't updated.
CSV export to google sheets, data split, then imported with TSV works fine as wiki describes. Feel free to re-read wiki.

Google Sheets
For your convenience I made an extra effort to make importing from Google Sheets extremely easy. There's only two steps:

Select (Ctrl-A) and copy (Ctrl-C) everything in the sheet.
Paste (Ctrl-V) the data into Import Frame and click Accept.
Note: This assumes there's only the required amount of columns present (i.e. no blank columns gets selected). You'd need to only select the columns with content otherwise.

Well, it's a great addon. Best I've used for LC. I'm using a bug as a feature and loving it, because I'm pasting TSV into the import window in game for ease of use and it's just working /shrug. I did need to export as CSV first to get the right headers.

I didn't look at the code, but whether you converting tabs to commas or I'm getting lucky, it's great either way.

Dude I made the addon and wrote the wiki, it's not supported 😂 and yes, I meant tsv export/import.
It's not just the header, the data in the tsv export is different, contains hyperlinks etc.

I'm fully aware that copying from Google Sheets technically is a tsv format, hence the "I made an extra effort to make importing from Google Sheets extremely easy" - doesn't change the fact that said data must have been exported as csv to begin with.

Edit: speaking of the wiki, you should probably read this - fairly certain it also says the same on the import window 😊

Still not a bug, but glad you like it.
I get it's confusing if you know your data formats, but in this case the names refer to both the format and the data/export itself - and it's the data that matters.