No, it's not. If Owain (the PhD who wrote his thesis in Welsh) wanted to be productive and advance his field, he would want his research to have the largest audience possible. Quoting the article: 'In his thesis, ‘Astudiaeth Gyfrifiadurol o Synthesis a Sefydlogrwydd Defnyddiau Mandyllog Anorganig’, Owain used computational science to see how porous materials could be used for green energy processes and sustainable ch…
Interesting observation, a language that hasn't evolved (due to lack of demand) to include scientific terms. Speaking zero Welsh I wonder if the choice for "density functional theory" was specifically chosen to sound "Welsh" instead of going for Anglicisation. Take Romanian, the word for "cheese" goes all the way back to Dacians, but there was no "density functional theory" until rather recently so that was borrowed…
Each of those three words was already a Welsh word - clearly Welsh already has words meaning “density”, “function”, and “theory” - so it seems the innovation is combining them in a new sense rather than making up new words as such.