This is the Threefold "Not" Manifesto. Whatever your exact opinion on Anglish is (which words to allow, and such) - first and foremost this is a project that removes loan-words and outside influence from English, and a very important thing is that Anglish still somewhat "feels" like English, rather than another language. This means we need to do things the "English" way and that's what pushed me to write this Manifesto.
Anglish is NOT Old English
While English - like its sisters, Angloscottish, and dead Yola - is a proud descendant of Old English, you shall not forget that "Old English" refers to state of the language spoken over 1000 years ago. This means that whenever you look up to words lost over time to loan-words, you shouldn't just go to Old English and update whatever word had a similar meaning in that time. Instead, your first step should be to look at the dialectal variety of English, as they still might keep a a needed word, then the next step is Middle English, which, remember, is still the direct continuation of the beloved Anglo-Saxon speech and still did not have as many loan-words.
Why is that?
It's a truism that language always changes, and obviously this applies to English. Words often change meaning over time, new words get crafted from old ones, and that isn't always due to outside influence. In fact such words with very reversed semantic shifts are strikingly rare in Anglish (deer to mean an animal) and these are just examples of absolutely no other native word fitting the meaning.
Anglish is NOT German
Purifying English off its loanwords ultimately leads to having more words in common with nearer related languages like German (such as shat to mean 'treasure', related to German Schatz of the same meaning) and this is all right. However, keep in mind, that English and German have had a separate history of their own for the last 1500 years and just because German or Dutch use a certain word certain way, doesn't mean that Anglish needs to do the same. Even though some of the most common English words like boy, girl, dog, pig are ones with unclear etymologies, we don't need to use young, maiden, hound, swine instead of them, and the same goes for any less common word, even ones pertaining to science (where pretty much all of them need to be crafted specially for Anglish).
If you feel like using prefixes like for- or be- to craft countless new words at hand - you need to rethink your approach, because it's not how English does things.
Anglish is NOT Latin
Large part of English wordstock is made of latinate words, many of which originate in highly learned / scientific literature. Obviously it's not even that specific to English only, nor we are likely to keep any of it in Anglish. But in getting rid of them, it's rarely wise to translate all the parts separately and then put together a Frankston monster. Even if languages such as German often do just that, it often doesn't seem natural in English, and such words are often hard to understand anyway.