TL;DR - I already have all the bugs reported!
Major factors affecting Naval template.
IF YOU PLAY ANY NATION WITH A STARTING TECH BELOW DIP 3, FLEET TEMPLATES WILL BE BUGGED.
This is due to the fact that certain ship classes are not unlocked yet for these tech levels. (For Korea for instance, they start with dip2. This means that they have access to building Light ships, Galleys, and Transports, but not Heavy ships.
For some unkown reason (to me, maybe the devs know and fix it already in their current unreleased builds)
you can not lower the ammount of Light Ships (trade ship/frigate class) even though you can...higher it. (english not doing so great, i'm sick wint pnuemonia..)
And you can not create new templates without the trade ships...
I have tested it across the entire map, with 40 or so nations of varying regions.
I have tested different starts, even using custom dates between the bookmarks.
If you want to play as korea/ming, or japan!
Click the kingdoms of the east start, and then, click above the year 1444 there are arrows above the 444 (not the 1)
it the decade arrow up until 1474, then lower the last one (year arrow) down 4.
1470 is the year that korea, china, chinese group, gets Dip Tech Three.
This Solves the issue.
BUT.
BE WARNED.
If you think you can play and unlock dip tech 3 from a ironman start at 1444, the template will STILL BE BROKEN, and heavy ship template options broken AS WELL when you unlock them, even though as long as you START the game with dip3 it is fine.

i have already submitted lot of reports on this, because fleet building is so precious and cute to me to watch my tiny boats float automatically into the base port XD
also bug reports are included that if you are an island nation, templates are entirely useless in some ways, like say you playing a uh... cyprus. first thing which you were to do, take lesbos, crete, naxos, corfu.
now that is all islands!
(another example is genoa, none which is connected to eachother!) they will not (even the navies which i think is silly some) build even if you set the ammoutn provinces to go to that number which they are.
setting 4 provinces in a template with genoa will not matter on base genoa, because clicking one province to start the template adds all four units to that province since it is no connected to other provinces. (none of genoa provinces are connected to other genoa provinces. this makes the entire feature useles,s which I UNDERSTAND for ummm....ummm... which i understand for land unites
but navy should be able to build in at LEAST shared sea zone, like say liguria/genoa and corsica which share it sea zone should build 2 from same template initiation.
I did not bother with army version to much, because building army cost manpower and i dont like using manpower. mercenaries is easier.