Here is a new version.
Now the mathtran server is called only once when the TeX formula is displayed for the first time. The baseline offset is stored in the Moodle database (in the cache_filters table) and used for further uses.
There is no need to call the mathtran server again and again to always get the same integer for the same formula.
Of course each client (but not the Moodle server) still call the mathtran server for each formula.