Symbolism is fine, but a light is a light. All lights give their own light. If no light, then not a light. Both the sun and moon were placed in the firmament between heaven and earth.
The bodies in the firmament are all angels. Celestial bodies are the angels.
I think you are confused about how the bible uses the word "light", and also in matters 'where' the Sun, Moon and stars (local Sol system) exist, and possibly the shape of the earth itself if I am reading you right.
I, as a true Seventh-day Adventist (from Roman Catholicism of 30 years), would like to share some scriptures (KJB), as all true Seventh-day Adventists, whose final authority in all matters of faith and practice is the Bible (which includes the gift of Prophets/prophecy, 1 Cor. 12:28, 14:32; Eph. 3:5, 4:11, &c.)
will acknowledge that the Earth is indeed a 'spheroid' (Isa. 40:22; Job 22:14; Psa. 19:6; 1 Sam. 7:16; Ecc. 1:6; Heb. 1:2, 11:3; 1 Sam. 2:8; Psa. 90:2; Isa. 3:18; Gen. 9:13-16; Eze. 1:28; Rev. 4:3, 10:1; Psa. 144:5; Isa. 45:6, 59:19; Mat. 24:27; Dan. 8:5; Jos. 12:1; Num. 2:3; Jos. 1:4; Deut. 11:30; Ecc. 1:5; Psa. 50:1, 113:3-4; Mal 1:11; Eze. 8:16; and the Sanctuary itself, among many other scriptures and examples.),
and the Spirit of Prophecy/Testimony of Jesus re-confirms this (sister White said that the "world" is "round", a "globe", an "orb" (just as Sun and Moon are), an "sphere" (when speaking of natural and spiritual matters).), see Letter 167, 1900, pp. 1, 2. (To G. A. Irwin, March 23, 1900.); Letter 167, 1900; 3SM 317; 10MR 9; ST, March 20, 1884 par. 6; CET 88; CCh 324; CT 185; DA 59-60; TA 111; ST, April 14, 1881 par. 11; EW 290; Ed 99; FLB 28; Hvn 155; HP 40; RH, August 15, 1899 par. 17; ST, August 3, 1904 par. 6; SW, January 24, 1905 par. 4; 13MR 382; AA 29; CME 30; ChS 18; CH 215; 6T 23, 24; CSW 133; CET 219; HP 93; LS 379; LS 402; MM 330; RC 121; 6T 23; 7T 51; Letter 183, 1899; TSA 83; AUCR, January 1, 1901 par. 6; GCB, October 1, 1901 par. 16; PUR, July 7, 1904 par. 2; RP, September 15, 1908 par. 4; RH, July 7, 1903 par. 7; CH 215; DA 822; FLB 94.6; AG 238.2; SC 68.1; 7T 51.1; ST Nov. 24, 1887; 1BC 1085.1; ST, July 18, 1892 par. 6; RH, January 18, 1881 par. 22; RH, May 31, 1887 par. 4; RH, January 24, 1882 par. 1; 1888 1370.2.
Just in case anyone asks.