Please help translate
 

Efectivamente, se podría haber desarrollado mejor, pero yo creo que hay......
As expected, it could/would have developed better, but I believe that there is...........

En cualquier caso, después podía haber abandonado a Martel y sigue con él..............
In any case, after he could have deserted to Martel and it follows with him.....

I'm not able to totally understand the last sentence without more context. Is the deserting an abandonment, or is it a change of allegiance? There's a difference. The shift in tense (pluperfect to present) baffles me. Why was that done?

I found those sentences on the internet. Way past my level of understanding.
I was trying to understand how poder is used in perfect tense.
I hope I've got it this time.

Past Perfedt
I could have bought the dress if I had known her size.
Yo podía haber comprado el vestido si yo había sabido su talla.

Conditional Perfect
I would have bought the dress if I had known her size.
Yo podría haber comprado el vesstido si yo había sabido su talla.

Future Perfect
Who could have bought her the dress?
Quién la habrá comprado el vestido?
I will have bought the dress by Monday.
Habré comprado el vestido para el lunes.

Here's how I would interpret these. It's not an exact science, since more context is really needed to correctly understand.

Efectivamente, se podría haber desarrollado mejor, pero yo creo que hay......
As expected, it could/would have developed better, but I believe that there is...........
Absolutely, it could have been developed better, but I think there's...

En cualquier caso, después podía haber abandonado a Martel y sigue con él..............
In any case, after he could have deserted to Martel and it follows with him.....
In any case, after that he/she could have left Martel and (but) he/she's still with him...

Your sentences make sense but I feel that they are complete in the sentence, then if you can write more in the sentence or at least you can finish to write them.

Suggestions above.

thanks all, i see that i need to review subjunctive again

Yeah, your original sentences broke into the "Si clause" rule, or that's what I call it at least. For example, "if I were _______, I would ______." Essentially, translated into Spanish, the verb that follows "si" would be conjugated imperfect subjunctive "like AngelicaDeAlquezar's usage of the word "hubiera." The second part of the clause "the I would" (or whoever is doing the action), would take the conditional tense.

For example,
"Si fuera Bill Gates, yo iría de vacaciones cada fin de semana"
("Si" followed by "fuera", second part, "iría."
Or: (Si + imperfect subjunctive, second part, +conditional).

EDIT: Sorry, I should pay more attention. This only goes for one of your sentences

Hi cmon,

Effectively/as a matter of fact, it might have been developed better, but I think there is...

In any event, could have abandoned Martel and (but) s/he is still with him...