Temporary. "Best would it be if you could lower the real skill
temporary because this would give you indeed faster gains." Maybe I should have inserted this word but I thought it was clear anyway, sorry.
I thought your skill gain was based on effective skill since you need to train with creatures that are appropriate for your effective skill level. If you have 95 real skill scrolled to 120, I don't think you'll get decent gains off a Gaman.
This is correct - assuming that 'effective skill' is the same as 'modified skill'.
You gain faster the lower your un-modified (or 'real' skill) is. A Satyr can discord you with 28% skill malus - which is temporary cast upon you. For example, if you have an unmodified (real) skill heigh or 100, after discording you will temporary have 72%. So you could gain faster if adequate (or appropriate) pets were around. Adequate means fitting to your modified skill in the sense of optimal chance for gaining. If you are discorded and still wear jewelry, you have to take this into account what to tame.
When you compare two methods to gain (whether jeweled-up or not, discorded or not), the essential condition is that the other parameters are equal, i.e. that you tame animals which are suitable for your modified (or 'displayed', 'effective' ...) skill. To see the modified skill, switch off the "Show Real" button in the skilll section in the 2D client. In KR toggle the "Real/Modified" button to "Modified". This skill heigh determines what to tame.
Model: Grandmaster Tamer with 100 real skill points:
Example: Alligator
50% success chance at 72 skill heigh (discorded, unjeweled) ->
Example: Gamans
62.8% success chance at 100 skill heigh (unjeweled) ->

100% success chance at 120 skill heigh (jeweled +20) ->
6.8% success chance at 72 skill heigh (discorded, unjeweled) ->

46.8% success chance at 92 skill heigh (discorded, jeweled +20) ->
Example: Nightmares
50% success chance at 120 skill heigh (jeweled) ->

10% success chance at 100 skill heigh (unjeweled) ->
0% success chance at 92 skill heigh (discorded, jeweled +20) ->

0% success chance at 72 skill heigh (discorded, unjeweled) ->
This is theoretically thinking because in Twisted Weald there are neither Gamans nor Nightmares nor Alligators. I choosed them just to illustrate the mechanism.