Running Lupdate reads the .pro file(s) and produces the ts files… for each language. In the case of measurements.pro
PMSYSTEMS +=
p0 p1 p2 p3 p4 p5 p6 p7 p8 p9 p10 p11 p12 p13 p14 p15 p16 p17 p18 p19 p20 p21 p22 p23 p24 p25 p26 p27 p28 p29 p30
p31 p32 p33 p34 p35 p36 p37 p38 p39 p40 p41 p42 p43 p44 p45 p46 p47 p48 p49 p50 p51 p52 p53 p54 p998
LANGUAGES +=
ru_RU
uk_UA
de_DE
cs_CZ
he_IL
fr_FR
it_IT
nl_NL
id_ID
es_ES
fi_FI
en_US
en_CA
en_IN
ro_RO
zh_CN
pt_BR
el_GR
Do the math and thats how many files there are.
Any time a tr() in the ui changes, running lupdate will generate changes in each of the ts files. It’s not likely much is going to change in the measurement files at this point… most changes are going to occur in the Seamly ts files.
I have no answer why random changes occurred in any measurement ts files. 
And that’s why I added a noTranslations option in the pro file… it can take an extra minute or 2 building in Creator as it copies or as the case is doesn’t copy all those files 1 by 1 - which will not change unless lupdate is run.