The first part of my argument is this: the word centrum still has a cognate in numerous modern languages, which use the TR letter order:
French: centre
Italian: centro
Czech: centrum # identical to Latin!
Swedish: centrum
[... numerous others ...]
The "TR" order of the letters in the "centrum" cognate is still alive in modern languages and their orthography, and so is even the "centrum" word itself.
The second part of my argument is that some contemporary dialects of English itself, like British and Canadian, use "centre"; using the "centre" spelling is a contemporary practice, and not a retrogression toward Latin.
The third part of my my argument is that changing "centre" to "center" is a gratuitous change that brings no benefit; it has no redeeming value.
Spelling it center provides the significant benefit of removing foreign orthography from English, making it easier to learn to read and write.
I see no value spelling it centre. That some other languages spell the word doesn't matter as they're pronouncing it without a vowel between the t and r which is rather different than English.
In French it's pronounced santr. In Italian it's sen-tro. In Czech it's tsen-troom. In Swedish it's sen-trum.
Languages that, like English, pronounce it with a vowel between the t and r? They spell it that way.
In Albanian it's qendër pronounced very close to rhotic English sen-ter.
In Norweigian it's senter (sen-ta) which is pretty close to non-rhotic English.
In Croation, it's centar (sen-tar).
In Lombard it's center.
In Swedish, the other word for center (meaning a center (place) or sports position) is spelled... center.
And even Czech, which spells it centrum, changes the spelling to center in the genitive plural, to match the pronunciation.
So even if we're going to choose spelling based on other languages, there's plenty that spell it similarly to center to argue for it in English - though I would still argue that other people are doing it isn't a compelling argument.