first of all which acacia are you using? the yield depends on the species, and as far as i'm aware there aren't many discovered acacia species with as high yields as mimosa hostilis around. acacia acuminata has a little more than hostilis around 1.5%.. acacia obtusifolia has round 0.4-0.6% .. sometimes higher..but is a bit variable. theres plenty more tryptamine containing acacias ... some which are a little more variable than the obtusi and acuminata but definitely worth looking into. in the collaborative research section you should read nen888's thread "trying to improve acacia information" .. for now i can't really comment on your yield without knowing the species you used
acacia generally works better with the A/B than the STB.. i see you used lextek.. it works ok. i would personally use less vinegar than the 1 to 3 parts ratio. little dash here n there .. apparently acacia is a little more sensitive to the lower ph. also a method which nen888 reccomends which is great prior to extraction is an ethanol soak before the acid boil(or adding ethanol to the acid boil). this ensures that you thoroughly strip the plant material of its alkaloids and less selectively than a regular acid cook ...meaning if there are other alkaloids present in the plant ethanol should get them out too which the acid cook may miss. the ethanol can then be driven off by diluting with water and heating until it no longer smells of alcohol. also what non polar solvent are you using?
what region are you in? theres a whole bunch of candidates worth looking into depending on your location