Spoiler
Rule 1 -- "Adjectivens Always After Nouns"
Adjectives come after the nouns they modify (as in Romance languages)

Rule 2 -- Nounsito plural like .*[aeiouy?]s .*[aeiouy?]ns nounbecome
Plural nouns ending with a vowel sound are pluralized with "ns", rather than the usual "s". Note that this applies to nouns ending with a silent consonant as well, such as "cow" -> "cowns".

Rule 3 -- I after E, except after C. Self-explanatory

Rule 4 -- Negativens alwaynsn't.
This rule, when directly translated, reads "Negatives do not always", a nonsensical statement. I believe this to be either a grammatical error on the part of the writer, or perhaps an undocumented but widely understood convention or abbreviation that makes sense to speakers of English 2 but confuses our English 1 sensibilities.
Historical analysis of the original text, however, reveals that in the early stages of English 2, this rule read "Instead of using "do not," verbs used negatively are conjugated as [verb + n't].", which, due to the similarities and common ancestry between early English 2 and English 1, is simple enough to understand.

Rule 5 -- Tense past tenhibit.
Past tenses are prohibited entirely. The convention instead seems to be to state the time the statement refers to, and then continue in present tense, as if that was the current time. It is unknown how hypothetical past tense ("I wish I was" etc) is treated in English 2, although I expect it is done in a similar manner, simply replacing verbs with their appropriate current tense form.

Rule 6 -- Namensito also capitalized namend.
The last letter of proper nouns is capitalized as well as the first. Unclear how this applies to contractions or possessives, although it's like that the final letter of the original name is capitalized, rather than anything added to the end.

Rule 7 -- [ck] t'[kk].
All occurrences of "ck" are replaced with "kk".

Rule 8 -- [n't]ito t'word modifeid n'ttaches.
Similarly to 4, phrases of the form "not <word>" become "<word>n't". A native English 2 speaker pointed out to me that this applies to contractions, even those not immediately obvious. Ie. "never" becomes "evern't", as "never" was historically a contraction of "not" and "ever".

Rule 9 -- Articlens t'[one].
All articles ("a", "an", etc.) are replaced with the word "one".

Rule A -- Adjective order thence: purpose, adjective proper, colour, shape, age, size, quality, quantity.
Self explanatory. Note the explicit inclusion of quantities as adjectives.

Rule B -- Verbsito ending with [b, k, d, g, t, ch] syllable o'word following verbtakes except when finishing sentence before modifications other, bu'for "one" instead [on] yousuffix taking care t'repeathn't [o], an'for "and" instead [an].
In certain cases, the syllable after a verb is attached to that verb. For this to occur, the verb must end with the letter/group "b", "k", "d", "g", "t", or "ch", and it cannot be the last word in a sentence, or directly before a comma. If the attached syllable is from the article "one", "on" should be appended instead. Likewise with "and" -- "an" should be appended instead. This process takes place after most other modifications, so make sure to apply the other rules, (G especially, as it tends to nullify any effect of Rule B) before applying this one.

Rule © -- "The"ito 'st'b'before nouns large used-one. Fo'nounsito small, yo'"Theed" youse-mustment. Your definitionito o'large an'small ma'devary.
"The" should only be used when referring to "large" nouns, and "theed" should be used for all others. The definitions of "large" and "small" are contextual, and depend on the speaker.

Rule D -- Wordsito o'syllablensito single an'fewer than letters four wordtractin t'theed word following except i'break obvious, theed letter final wordrasing, excepting [is] t'['s].
Single syllable words of three letters or less should be contracted and attached to the following word, replacing the final letter with an apostrophe, except in the case of "is", which is abbreviated to "'s". This takes place after the application of all previous rules, including Rule B. Should be avoided if it results in ambiguity. Note that words which are not ordinarily single-syllable may become single-syllable words after the application of Rule B, and are therefore affected by Rule D, ie. "into water" would remain as it is, but "jumped into" would become "jumpedin t'water".

Rule E -- Adverbnsito their verb adfollow, separated b'dash an'i'their form noun.
Adverbs come strictly after the verbs they modify, separated by a dash, and converted to nouns. Ie. "Run fast" becomes "run-fastness".

Rule F -- Theed nounito subject main o'on'verb, after pluralization, have [ito] nounppendedto theed end, theed vowel final i'i'ends i'one nounplacing.
The main subject of a verb has "ito" appended to the end. This occurs after pluralization. If the noun ends in a vowel, the final vowel is removed before "ito" is added.

Rule G -- Verbsito except [be] their predicate verbpostcede. Syllablito first o'it'actor (or [huh] i'actor unknown) syllable first o'verb sylreplace i'verbito 'sthree syllables o'more, sylprecede-other.
English 2 follows SOV order. The first syllable of the actor is prepended to the verb (if the root verb is shorter than three syllables), or replaces the first syllable of the verb (if the verb is longer than three syllables and replacing the first syllable does not change or confuse the meaning of the sentence). If the actor is unknown or it does not make sense for the verb to have an "actor", the syllable "huh" is prepended to the verb. Note that this rule applies before Rule B, and in most cases, nullifies it.

Rule H -- Theed endingito [er] o'on'adjective comparative 's-stead [ing]. Theed endingito [est] o'on'adjective superlative 's-stead [ed].
The comparative ending "er" is replaced by "ing", and the superlative ending "est" is replaced by "ed".

Rule I -- Rule new: Yoito D rule ma'b'youusen't i'emphasis emphquire.
The contractions mandated by rule D may be omitted for emphasis.