Welcome to the forums!
Some feedback:
Bobbsey Twins = Los Gemelos Bobbsey (the last name of the twins simply follows the designation)
la familia Bobbsey = the Bobbsey family
Place names may or may not need to be translated. It depends on how familiar the place is to your audience. Because Rainbow Valley (
(el) Valle del Arco Iris) may not be familiar to all, you could leave it untranslated.
I'll let you in on a little secret. The professionally-translated version of the book totally skirts the question of whether to translate the place name or not by using a totally different title: "
Los gemelos en las cataratas del misterio"
As you can see, the English last name of the twins is also missing from the title, as it is in the entire series.
Word-for-word translations
seldom work. This is a hurdle we all must face when trying to translate. It is usually a much better idea to start with a novel written in
Spanish and translate it into English. This will help you learn the flow of the language and will help you see how the words work together.
English word order
seldom matches Spanish word order.
For example:
There's nothing here but milk and eggs
=
Aquí no hay nada más que leche y huevos (a double negative is a must in Spanish - here 'but' is translated as 'more than')
The interjection "Here," is seldom translated into Spanish.
Let me take a look.
=
Déjame echar un vistazo. (
echar un vistazo) (you can use the simpler '
déjame ver' ('let me see'))
We just have to have some raw meat
=
Sólo tenemos que tener carne cruda ('
tener que + infinitivo' = 'have to + infinitive' - 'some' is never translated when the noun is uncountable)
I think 'for our drag' is a reference to the artificial scent trail used in a 'drag hunt'. You'll want to look up how to say 'artificial scent trail' and use the four-word translation for the word 'drag'. I'll give you a hint; the word for 'trail', in this sense, is '
rastro'. Since that noun is singular, 'our' can't be translated as '
nuestros'.
When you relate a story that happened in the past, the majority of the verb conjugations will be in the imperfect tense. That's a tense you haven't studied yet, so you're asking a lot of yourself.
The twins 'tenían seis años' (were six years old), but most would just say "
Los gemelos (Bobbsey), de seis años, estaban de pie delante de la nevera."
You can usually
find a synonym for troublesome words or phrases.
Technically, the '... was poked inside' clause is an example of the passive voice. The passive voice isn't used nearly as often in Spanish as it is in English and you should learn how to express the same idea using one of two methods. I won't delve into this further, but will say that a synonym of 'poke inside' is 'insert'. Using '
meter' would yield a better translation than what you tried ('
asomar' = 'stick out'). It's even possible to substitute a past participle, used as an adjective:
con la cabeza rubia de Flossie metida en ella (la nevera)
una voz detrás de los gemelos les sobresaltó ('
voz' is the subject, so the verb will be in the singular third-person instead of the plural third-person)
That's all I have the time for now, but perhaps others will give you other things to think about.