I have never claimed any language to be perfect.
And you’re confusing “scientific theories” with definitions and word usages.
Scientists are not disagreeing with definitions or meanings of the some words, nor how words are used, YoursTrue.
What they disagree with, are the theories. Scientists are supposed to be looking at different alternatives (eg different hypotheses), they are supposed to be skeptics. They are supposed to be challenging the data, so they would as much test current accepted theories as they would test new hypotheses.
The strength of any accepted theory, is how well they face rigorous testing, with evidence, experiments & data still verifying the evidence.
For example. As this topic, is about Evolution, is that began almost 200 years ago, in his voyage onboard HMS Beagle from 1831 to 1836, Charles Darwin explored parts of the world like Argentina, Chile, Galapagos & other islands in the pacific, Australia & South Africa, examining living plants and animals, not fossils (he only really studied fossils after he returned home at the Geological Society (of London) and at museums & universities). he noticed that at islands of Galapagos and the mainland South America as the different species of finches and different species of tortoises. He examined all sorts of wild life and plants in that journey, wrote copiously notes and drew many sketches in his journals. He noticed that different islands nearby to each other (Galapagos) that have different climate patterns and different terrains, can different species of the same plant genera, or different species of finches, or different species of tortoises, can have traits that differ from one another.
Those journals were starting point of his research into speciation, that formed the basis of Natural Selection, one of the mechanisms in evolutionary biology. What he found that he later recorded in On The Origin Of Species (1859) and in other works, that environmental factors, when environment changed, environments are driving forces for change (eg adaptability & speciation).
It has been 165 years since the publication of On the Origin, but since his death, biologists have revised and updated Natural Selection, with new observations, evidence & data, with new testing methodology (eg DNA testing & analysis, morphological analysis, clade taxonomy, etc), and of newer fields in biology (eg modern genetics, molecular biology, biochemistry, etc), all of these brought forward Natural Selection into the 21st century. Natural Selection are today, more robust than the times of Darwin and his contemporaries, eg Albert Russel Wallace (another pioneer of Natural Selection), Joseph Dalton Hooker, Thomas Henry Huxley, Gregor Mendel (whom Darwin never knew about, the pioneer of modern genetics).
Biologists and paleontologists don’t deny speciations, what they may disagree with, are mainly classifications of certain species to certain genera or families.
Look at the hyenas for example. They have certain traits and features (especially their behavioural) that are canine-like, but others that are more feline-like. So which would you put “canine” or “feline” carnivore group?
Well, DNA comparisons showed that are actually more closer to feline than to canine. And yet biologists still debate between these 2 sides.
Sometimes classifying organisms are clear cut, but at other times they are not so. But regardless of whether they are for or against one side or the other, they don’t deny speciations in evolutionary biology.