NASA Scientist says Einstein mistranslated
According to NASA scientist (retired) Dr. Edward Dowdye: the scientific writings of Einstein have been mistranslated from German into English.  Dr. Dowdye is fluent in English and German,  and part of a community of scientists who are questioning the relativity theory. He said he has gained the respect of a number of renowned physicists who agree with his stance. 
I have looked into this issue and given talks comparing the usual translation of Einstein’s 1905 paper on relativity with a newer translation. 
It appears that Einstein was not fluent in English and was talking in his native language of German to English-speaking audiences even in 1931 while in Oxford, England.  Thus he had to rely heavily on his translators, but what seems to have happened is they did not translate properly the nuances and subtleties from one language to the other, and also have mysterious omissions and additions added to the English translation which are not in the original German paper. The end result of this is: in the original German it is a different theory to what it has been translated to in the English.
The usual version of Einstein's 1905 paper on special relativity entitled “On the Electrodynamics of Moving Bodies” appeared in the book “The Principle of Relativity”, published in 1923 by Methuen and Company, Ltd. of London. Most of the papers in that collection are English translations by W. Perrett and G.B. Jeffery from the German Das Relativatsprinzip, 4th ed., published by in 1922 by Tuebner.
As an example of an addition: In Part 1 Section 1 the translation has: “Let us take a system of co-ordinates in which the equations of Newtonian mechanics hold good.” With footnote: “i.e. to the first approximation.” But the footnote is not in the original German paper. This mysterious addition changes what Einstein is saying from Newtonian mechanics holding good to it only being an approximation.
As an example of an omission, a lot further on: The German has “In einem elektromagnetischen Felde bewege sich ein punktförmiges, mit einer elektrischen Ladung versehenes Teilchen (im folgenden „Elektron" genannt), über dessen Bewegungsgesetz wir nur folgendes annehmen:” Translates by Google translator as: “In an electromagnetic field move a point-shaped particle provided with an electric charge (in the following called "electron"), about whose law of motion we assume only the following:” Probably the term “point-shaped would be best translated as point-like; Google translator only giving rough translation. But the usual translation completely omits point-shaped or point-like particle and says instead: “Let there be in motion in an electromagnetic field an electrically charged particle (in the sequel called an “electron”), for the law of motion of which we assume as follows:”
Einstein was talking about point(like/shaped) particle and the translators seem to want to cover that up completely in that particular sentence. The whole translation they present is full of these glaring omissions and additions which we discover when we try to compare their translation with the original German. In conversation with one person as we compared the translation, we agreed that the translators must have had an agenda- a bias as to how they want to present the theory and did not want to present a faithful translation.
The most problematic translation occurs with what is presented as to how Einstein deals with time. The translators translate as: “But it is not possible without further assumption to compare, in respect of time, an event at A with an event at B. We have so far defined only an “A time” and a “B time. We have not defined a common “time” for A and B, [for the latter cannot be defined at all unless we establish by definition] that the “time” required by light to travel from A to B equals the “time” it requires to travel from B to A.”
The problem part placed in square brackets: [for the latter cannot be defined at all unless we establish by definition].
Should read: “the latter time can now be defined in establishing by definition that the ‘time’”.
This represents two different things as far as I am concerned; the first translation stating that time can only be dealt with in a certain way when it states “cannot be defined at all unless...” But the second translation having no such restriction on how time is to be dealt with.
This mistranslation was noted in 1963 in the American Journal of Physics, and reprints do not correct the mistake.
Adolf Grünbaum referring to this issue in Philosophical Problems of Space and Time: Second, enlarged edition,  says:
"Perrett and Jeffrey unfortunately mistranslated the pertinent sentence in his original 1905 German paper into English. Hence their mistranslation can be mistaken as documentary proof that Einstein himself erroneously asserted that simultaneity can be specified in the STR [special theory of relativity] only by stipulating the equality of the to and fro velocities of light. But in Einstein's original German text, he had offered the stipulation of the equality of these one-way velocities as a (contextually) sufficient condition for simultaneity, and not as a necessary condition."
What this means is there is really a problem in the logic of what is said in the German to how the logic has now been presented in the translation into English.
On top of all the other problems with Einstein’s writings on relativity such as many critics pointing out maths problems, it seems hard not to think that the mess made in the translation was not a deliberate attempt to set up more obscuration.
 Personal communication
 Former NASA Physicist Disputes Einstein’s Relativity Theory, by Tara MacIsaac, Updated: June 17, 2014
Book: Discourses & Mathematical Illustrations Pertaining to the Extinction Shift Principle Under the Electrodynamics of Galilean Transformations, Third 2012 Edition, Edward Dowdye.
 CNPS 2019 - Roger Anderton - Einstein Mistranslated https://www.youtube.com/watch?v=eCfzuAZi_rA
 Einstein in Oxford, Physics World, June 2019
 Mistranslation of a Passage in Einstein's Original Paper on Relativity, American Journal of Physics 31, 398 (1963); https://doi.org/10.1119/1.1969543 Charles Scribner Jr.
 Philosophical Problems of Space and Time: Second, enlarged edition. By Adolf Grünbaum p 702
CNPS 2019 - Roger Anderton - Einstein Mistranslated