Hebrew is not a difficult language to learn. Due to several thousand years of forced stagnation, it failed to develop new roots and became quite regular. The result is that each “root” learned allows the learned to understand countless new words. To demonstrate, the root katav כתב is used in many words, write, letter, address and dictate, to name just a few. Furthermore, there are only three tenses, past, present and future, simplifying grammar use. The number of exceptions is rather limited and carefully organized into categories. Thus, despite its initial impression, learning Hebrew is not an especially difficult task.
That said, native languages always interfere in one way or another with foreign languages. I have lived in Israel some 28 years and am quite fluent in both speaking and reading. Yet, I continue to repeat certain errors despite all of my wife’s corrections. It is as if my brain insists on certain ways of doing things.
In my case, this inability to adjust to Hebrew comes out in three areas: letter pronunciation, syntax and gender chaos. Regarding the first, the transition from one language always involves some problematic sounds and letters. For example, the French truly struggle with the English th sound. In the case of Hebrew, I pronounce the voiced and unvoiced h sounds, as represented by the letter heh ה, het ח and hof כ almost without any distinction even though they are three different sounds in fact. Likewise, I massacre the difference between the sounds of the letters alef א and ayin ע although I am cognizant of it.
Every language has its own syntax, its own way of framing the sentence, which can lead to misunderstandings when applied to another language. A nice example is the American expressing her frigidity instead of lack of body heat in the classic direct translation of English to French: Je suis froide when it should be J’ai froid. Regarding to Hebrew, since English sentences require a subject and verb, it is common and acceptable to add “it is” before adjectives to arrange the grammar while in Hebrew there is no need in some cases. So, I constantly say זה קר בחוץ, literally it is cold outside, instead of just קר בחוץ , cold outside. It just does not seem natural.
Finally, the whole genderification of pronouns is a constant trap. All pronouns, 1st, 2nd and 3rd person, have a male and female form in both singular and plural. By contrast, English has he and she, with all other pronouns being neutral, such as I and they. Not only that, the Hebrew verb must agree with the gender and number of the noun, unlike the non-gender specific forms of English verbs. The result is the constant need to consider the gender and adjust the grammar. When speaking quickly or under pressure, these details can get lost. In my case, everybody else in my house, i.e., my wife and daughter, is female, leading me to always use the female forms. Unfortunately, quite often that rule does not apply out of the house, leading to people to think “what a stupid American.”
In summary, language interference is a part of the learning process. To a large extent, it can be overcome most of the time. Still, no matter how long I will live her and how well I know the language, English will interfere from time to time. Ultimately, it is not that important.