Ygtjki

The word "xeroxed" is an example of conversion. Conversion means the change of a word class without a change in form. It is very productive in English. For example, I can use the noun bottle and turn it into a verb he bottled the milk, or the adjective green and turn it into a noun we went out into the green, an ungradable adjective like English and turn it into a gradable adjective, he is very English, etc. In your case, you took a proper noun, Xerox, and turned it into a verb, to xerox. That does not make the resulting word a "proper verb", which is not even a recognized category in linguistics. It makes it a verb converted from a proper noun.

No, there are not "proper verbs." There are verbs, which communicate an action, and then there's everything else.

Your example is not an instance of metonymy, as @user307254 suggested. Metonymy is a method of figuratively conflating one object or concept with the name of another, with which it is associated, for the purpose of metaphoric expression. To wit: saying "lay off the bottle" to mean "quit drinking" is metonymy.

What you have described is a phenomenon referred to as "anthimeria" by etymologists. It is sometimes colloquially termed "verbification," and it is a perfectly normal (and acceptable) aspect involved in the evolution of language. The process is not so much a problem of linguistics as it is a legal concern, resulting in so-called "genericide;" it primarily relates to intellectual property as it can result in the loss of trademark (Bayer lost its claim to the word Aspirin in 1921 due to generalized use of the word).

As a rule, the trademark will be capitalized, since it is a proper noun, whereas the verbal form with be lower case. You may have an account with Google, but you could just as easily use another search engine to google your query.

If it's listed in the dictionary as a verb, rather than slang, then it is as "proper" as any other. According to the three dictionaries I referenced (Merriam-Webster, Dictionary.com, and The Cambridge Dictionary of English), xerox is recognized as a verb, while Windex is not. An entry for windex was only included in the Urban Dictionary, suggesting that it is merely slang.

Thus to xerox is "proper," yet to windex is not.

Addendum

Since this answer appears to be mildly ambiguous, I will attempt to provide a laconic conclusion: no, there is not a verbal analogue to proper nouns.

The Cambridge Dictionary gives the capitalised verb:

Google

On the basis that dictionaries are authorities on whether a word is a word or not—at least for pedants—English does indeed appear to have proper verbs, so to speak.

Your examples illustrate metonymy

: a figure of speech consisting of the use of the name of one thing for that of another of which it is an attribute or with which it is associated.
(https://www.merriam-webster.com/dictionary/metonymy)

Another example of the metonymy is
boycott.

According to Etymologyonline:
1880, noun and verb,
"to combine in refusing to have dealings with, and preventing or discouraging others from doing so, as punishment for political or other differences."

From Irish Land League ostracism of Capt. Charles C. Boycott (1832-1897).

While being a life long user of the English Language. Having written many presentations for public consumption. Also the editor (especially tense) for NIH grants, and various other IT and Academic technical publications.

I do not recall the term, in English proper verb. There are adverbs to install additional fortitude to a verb. Not a proper verb. Some Germanic languages do use a variety of verb types, German, Dutch, Flemish, Danish, languages for an example.

The conjugation of verbs is a "whole other country" that have been removed in US English. I can not speak to the other English Flavors, GB, CA, CA-NF, CA-BC, NZ, AU, SA, ... idk how many there are?

Verbs in Deutsch are quite complex and multi-leveled. In German class, verb conjugation is/was called "diktat".
You may see a pattern. It was about as difficult as memorizing the Periodic Table.

Present - singular & plural
Compount Past - singular & plural
Past Perfect- "" ""
Future Tense - "" ""
Furture Perfect - "" ""

There are three command (imperative) forms.
The subjunctive is a mood, not a tense. also Singular & Plural.

The Subjunctive II is based on the simple past tense (Imperfekt). Singular & Plural.

I got this from my German 2 textbook "Spreken und Lesen" Speaking & Reading.

I hope I didn't go too far, but there are "Parts" of the German language being sloshed into common English. Uber, Verboten, are a few examples. Super - Higher & Forbidden.