I hope some TeamSpeak guy will pass here.
I've found a more important issue.
I was wondering why I couldn't get like one month of field data using timescale to preserve bandwidth.
Whatever the TimeScale parameter I use, it only gives me 34 hours of last data ( one data each 15 )
It seems the Timescale filtering is applied after the export limit. 
I mean, if you have like 2 102 400 entries in your channel corresponding at sensors updating each 15sec for a year, and you want to grab this year of data with a timescale of 1440, this should gives 1460 entries. Far better than grabing the 2102400 just for generating a year graph.
But you can't because it will filter the last limited entries (looks to be 8000 ) giving only 5 result ( 8000/1440)
There's no sense of having a timescale parameter capable of 1440 if the source data is filtered before to the last 8000 entries.
It should work the other way, first it filters data with timescale from your database, then if there's more than the limit, only deliver the last 8000..
This looks more a bug than a feature, or have I missed something ?
Any input from ThingSpeak devs?
Thanks