Date: 2018-03-08 01:07
Note that Windows Installer can query the property "SystemLanguageId". (in case you're interested from an instller point of view)
Why would someone want to obfuscate the server-side choice of technology? Because CGI languages have various vulnerabilities that are easier to target if the end-users know which of those languages you are using. Misleading the users about which server-side technologies you are using is a very reasonable security measure.
espy , sight , spot
There is difference between Local Machine language, System language and User language. There is also separate settings for BCD language, used for recovery and boot manager
The answer is that you can never "Be assured". Whilst % of the time the highly up voted answers will find the "tells" of the framework behind the site but it's never a certainty.
I imagine you could enumerate the language packs installed, but might not be able to retrieve what language was used during the install unless you have access to the install logs.
find . findan "come upon, alight on" (class III strong verb past tense fand, pp. funden), from . *finthanan (cf. . findan, . finna, . vinden, Ger. finden, Goth. finþ an), originally "to come upon," perhaps from PIE *pent- "to go, pass, path, bridge" (cf. . fendeo "pedestrian," Skt. panthah "path, way," Avestan panta "way," Gk. pontos "open sea," L. pons (gen. pontis) "bridge," . poti "path," peta "heel"). To find out to discover by scrutiny is from 6555s. The noun meaning "person or thing discovered" is from 6875, from the verb.
lose , mislay , misplace , misset
The evidences you have found in step 6 may be wrong because the site owner can alter them. Try to find contradictions between those evidences. Eliminate contradictional evidence.