The usage in English of foreign words, particularly those from languages with gender differences, is best clarified using a style guide. It is to be noted that some style guides suggest using Filipino as the adjective for both sexes. if you are writing for publication, or for academic purposes, you should consult the relevant style guide. If you are writing for yourself, you can choose Filipino or Filipina as the adjective, but remember to be consistent.
the Philippines inhabited by Filipinos (male) and Filipinas (female);
adjective Filipino for both sexes, but Philippine for, say, a
Philippine island or the Philippine president
Guardian and Observer Style Guide (P)
Philippine, Filipino, Filipina Adjective form of place-name. The
Philippines takes a singular verb.
Filipino is the official language and the noun and adjective form for
a native of the Philippines.
Filipina may be used to specify a Filipino girl or woman.
Philippine, Filipino, Filipina (National Geographic Style Manual)
Adjective form of the Philippines
Philippine is generally used with inanimate nouns. Examples: the Philippine National Anthem, the Philippine Senate.
Philippine is also used as an adjective for people when it describes people representing the Philippine nation. Examples: the Philippine president, the Philippine ambassador, a Philippine politician, the Philippine goalkeeper.
Note that Philippine cannot be used as an adjectival noun: The Philippine was talking to the Frenchman is not idiomatic English.
Filipino is used as an adjective and adjectival noun to refer to male Philippine citizens or people with Filipino ancestry: Examples: a Filipino actor, He is [a] Filipino. It is mainly used for males or mixed-gender groups, or where the gender is unknown. Example: Many Filipinos believe ...
Filipino may also be used with inanimate nouns, though it is more commonly >applied to people. Examples: Filipino jeep, Filipino pottery.
Filipino is also the name of the national language. Examples: She speaks Filipino, Filipino-speakers.
Filipina is used when referring to women, both as
an adjective and as an adjectival noun. Examples: a Filipina poet, The
company is run by a Filipina.
Filipino women is an expression that is mainly used outside the Philippines and should be avoided in Philippine-related articles; in Philippine English, standard usage is Filipinas, Filipina women or, more rarely, Philippine women.
Pinoy and the feminine form Pinay are the slang equivalents to Filipino and
Filipina respectively, and apply to people only. Pilipino or Pilipina
are rarely used in English. They may be found in the former name of
the Filipino language as well as in the acronym OPM, or Original
Phillippino, Phillipino, Philippino, or Philipino are
Wikipedia Manual of Style (Philippines-related)