The limit is already too low. The privilege levels for this site are still in "beta" mode, which is a starting point for fledgling sites just getting their feet wet. In all honesty were stuck halfway between being very well established and being too small to be worth SE's time to graduate us.
Developing a taxonomy for the site should be left to those with both a lot of domain expertise and familiarity with the SE system in general. You don't want a constant influx of new ideas to be played out through tug of war. Hence you want a few of the most experienced users to handle those functions.
Site newcomers and even regular long term participants often mistake the function of tags and start treating them like hashtags to spice up posts the way they get used on Twitter and Instagram. That's not what they're for and you want to minimize the lurch that such users can create. Hence creating new tags is also capped to a certain reputation threshold.
Synonyms should clearly be a much higher threshold. Noticing whet existing tag usages start to get conflated requires people paying a lot more attention. Additionally the potential for damage done by flattening tags in the event of a bad synonym is much greater.
If anything, 1250 is too low for this site and we would be better off with the graduated site level of 2500.